Archive for May 2021

Most fall flowering plants are

09:20

Most fall flowering plants are



A) long-day plants

B) short-day plants

C) short-night plants

D) day-neutral plants



Answer: B) short-day plants

Which of the following is an example of how photoperiodism affects plant ecosystems?

09:19

Which of the following is an example of how photoperiodism affects plant ecosystems?



A) Spinach, a long-day plant, flowers in the tropics because the days are so long.

B) Ragweed, a short-day plant, can't flower in the northern US because of the frost in the late summer months.

C) Cockleburs, a short-day plant, can live where there are long flashes of red light at night.

D) Chrysantheums, a short-day plant, bloom in the summer when the days are long.



Answer: B) Ragweed, a short-day plant, can't flower in the northern US because of the frost in the late summer months.

Which of the following is an example of a chemical defense mechanism in plants?

09:19

Which of the following is an example of a chemical defense mechanism in plants?



A) A plant tastes bitter when a herbivore attempts to eat it

B) The leaves of a holly plant are slippery, making them difficult to eat

C) Thorns on the stems of pear bushes detract herbivores

D) The leaves of sensitive plants close up rapidly when they are touched



Answer: A) A plant tastes bitter when an herbivore attempts to eat it

Short-day plants

09:18

Short-day plants



A) will flower if a period of continuous darkness was longer than a critical period.

B) flower in days where the day is short or the day is long.

C) flower when a period of darkness is shorter than the day.

D) flower if the night period is interrupted by a flash of light.



Answer: A) will flower if a period of continuous darkness was longer than a critical period.

To qualify as a circadian rhythm, the activity must

09:18

To qualify as a circadian rhythm, the activity must



A) occur in the morning and the evening

B) occur only in the presence of external stimuli

C) be able to reset if external cues are provided

D) affect seasonal changes



Answer: C) be able to reset if external cues are provided

A researcher discovers that cocklebur will not flower if a required dark long period is interrupted by a brief flash of white light. Which of the following conclusions can be made?

09:17

A researcher discovers that cocklebur will not flower if a required dark long period is interrupted by a brief flash of white light. Which of the following conclusions can be made?



A) A cocklebur is a long-day plant.

B) When the night is longer than a critical length, the cocklebur will flower.

C) The length of the light period controls flowering.

D) Interrupting the light period with darkness will prevent flowering.



Answer: C) The length of the light period controls flowering.

Plants in a high-humidity environment will

09:16

Plants in a high-humidity environment will



A) close their stomata due to the low water potential outside the leaf

B) open their stomata temporarily then close due to environmental stress

C) close their stomata due to the high water potential outside the leaf

D) keep their stomata open due to the electrical potential of the guard cells



Answer: D) keep their stomata open due to the electrical potential of the guard cells

Phytoremediation is effective because

09:16

Phytoremediation is effective because



A) it is much quicker than conventional cleanup of sites

B) it can be effective at extremely deep sites by plants with taproots

C) plants have unique abilities to absorb and tolerate toxic substances

D) toxins absorbed by the plant increase reproductive rates of the plants



Answer: C) plants have unique abilities to absorb and tolerate toxic substances

Plants do not acquire nutrients by which of the following mechanisms?

09:16

Plants do not acquire nutrients by which of the following mechanisms?



A) engaging in a mutualistic relationship with fungi

B) sending out rootlike projections that tap into vessels of a host plant

C) possessing root nodules containing nitrogen-fixing bacteria

D) breaking down dead organisms extra-cellularly for sugars



Answer: D) breaking down dead organisms extra-cellularly for sugars

Sucrose is moved into the phloem by

09:16

Sucrose is moved into the phloem by



A) passive transport

B) active transport

C) phagocytosis

D) diffusion



Answer: B) active transport

The primary function of companion cells is to

09:15

The primary function of companion cells is to



A) provide proteins to sieve-tube members

B) transport organic nutrients to all parts of the plant

C) allow water to pass from cell to cell

D) provide internal support



Answer: A) provide proteins to sieve-tube members

The cells of a wilted plant have a

09:15

The cells of a wilted plant have a



A) higher water potential inside the cell

B) higher concentration of solutes outside of the cell

C) lower osmotic potential outside of the cell

D) lower pressure potential in the extracellular liquid



Answer: B) higher concentration of solutes outside of the cell

The presence of a vascular transport system

09:15

The presence of a vascular transport system



A) does not allow plants to increase in height

B) facilitates the dispersal of spores

C) makes it more difficult for animals to recognize flowers

D) promotes easier distribution of nutrients to fast-growing tissues



Answer: D) promotes easier distribution of nutrients to fast-growing tissues

Which of the following is true about the bark of a tree?

08:29

Which of the following is true about the bark of a tree?



A) Secondary phloem is not produced every year.

B) Phloem builds up from season to season.

C) Girdling is not harmful to a tree.

D) Cork cells have a waxy layer that makes them waterproof.



Answer: D) Cork cells have a waxy layer that makes them waterproof.

In double fertilization,

08:28

In double fertilization,



A) the microsporangium divides by meiosis

B) the pollen sacs produce microspores

C) meiosis produces four megaspores

D) one sperm fertilizes the egg, the other forms an endosperm nucleus



Answer: D) one sperm fertilizes the egg, the other forms an endosperm nucleus

Ginkgoes are dioecious, which means that they

08:27

Ginkgoes are dioecious, which means that they



A) produce microspores and megaspores

B) have male and female reproductive structures

C) have separate trees producing seeds and pollen

D) are pollinated by insects via wind



Answer: C) have separate trees producing seeds and pollen

Microphylls differ from megaphylls in that they

08:27

Microphylls differ from megaphylls in that they



A) are more broad

B) have a single strand of vascular tissue

C) are found in ferns

D) can gather more sunlight



Answer: B) have a single strand of vascular tissue

Flowering plants and gymnosperms are divided by

08:25

Flowering plants and gymnosperms are divided by



A) the type of fruit

B) mode of embryo protection

C) apical growth

D) the type of vascular tissue



Answer: B) mode of embryo protection

Fungi produce spores

08:25

Fungi produce spores



A) during asexual reproduction only

B) during sexual reproduction only

C) during asexual and sexual reproduction

D) because they are hermaphroditic



Answer: C) during asexual and sexual reproduction

The relationship between fungal and algal cells (lichen) is

08:24

The relationship between fungal and algal cells (lichen) is



A) mutualistic, in which the fungus receives nutrients from the algal cells, and the algal cells are protected from dessication by the fungus

B) controlled parasitism, with the fungus receiving nutrients, and the algae not benefiting at all from the interaction

C) commensal, with the fungi getting no benefits from the algae

D) a predator-prey relationship, as the fungi feeds on the algae



Answer: B) controlled parasitism, with the fungus receiving nutrients, and the algae not benefiting at all from the interaction

What adaptation ensures that terrestrial fungal offspring will proliferate?

08:23

What adaptation ensures that terrestrial fungal offspring will proliferate?



A) Fungi reproduce only asexually.

B) Fungi reproduce asexually through the use of runners.

C) Fungi produce nonmotile gametes during meiosis.

D) Fungi produce spores during both sexual and asexual reproduction.



Answer: D) Fungi produce spores during both sexual and asexual reproduction.

The infection caused by ringworm is due to

08:23

The infection caused by ringworm is due to



A) the secretion of toxins that suppress the immune system.

B) the production of lesions that produce penicillin.

C) the release of enzymes that degrade keratin and collagen in the skin.

D) the digestion of cellulose in the cell walls.



Answer: C) the release of enzymes that degrade keratin and collagen in the skin.

Which of the following is a primary difference between plants and fungi?

08:23

Which of the following is a primary difference between plants and fungi?



A) Fungal cells lack chloroplasts

B) Plant cell walls are composed of peptidoglycan

C) Fungi lack motility at any stage in their life cycle

D) Many plant cells are multinucleate



Answer: A) Fungal cells lack chloroplasts

Conjugation in paramecium is an extraordinary process, as

08:22

Conjugation in paramecium is an extraordinary process, as



A) genetic recombination occurs in the two cells that begin the sexual process

B) it is a reproductive process

C) it is not a sexual process, but a reproductive process as four daughter cells are produced

D) clones are produced with an identical, equal amount of DNA



Answer: A) genetic recombination occurs in the two cells that begin the sexual process

In alternation of generations, the sporophyte produces

08:21

In alternation of generations, the sporophyte produces



A) haploid spores by meiosis

B) haploid gametes

C) diploid gametophytes by mitosis

D) diploid zygotes



Answer: C) diploid gametophytes by mitosis

Contractile vacuoles

08:21

Contractile vacuoles



A) form psuedopods

B) discharge excess water

C) are essential in reproduction

D) contain carotenoid pigments



Answer: B) discharge excess water

Dinoflagellates reproduce

08:20

Dinoflagellates reproduce



A) asexually by mitosis and sexually by meiosis

B) through binary fission

C) by sexual reproduction through conjugation

D) with the aid of sex pillus



Answer: A) asexually by mitosis and sexually by meiosis

Protists are NOT

08:19

Protists are NOT



A) unicellular

B) colonial

C) filamentous

D) prokaryotic



Answer: D) prokaryotic

Cells prefer to use glucose over other energy sources. Therefore, in prokaryotes,

08:19

Cells prefer to use glucose over other energy sources. Therefore, in prokaryotes,



A) high levels of glucose will prevent expression from other operons that metabolize lactose.

B) low levels of glucose will cause the lactose mechanism to be turned off.

C) cAMP binds to activators to slow down transcription of the lac operon.

D) lactose will be synthesized only when there is ample glucose in the cell.



Answer: A) high levels of glucose will prevent expression from other operons that metabolize lactose.

Under what conditions are repressible products made in prokaryotes?

08:19

Under what conditions are repressible products made in prokaryotes?



A) when the substrate is in the environment and needs to be metabolized.

B) when a signal molecule is scarce.

C) when a metabolite activates the repressor.

D) when a repressor is in its active form.



Answer: B) when a signal molecule is scarce.

Which of the following is a post transcriptional modification in eukaryotes?

08:18

Which of the following is a post transcriptional modification in eukaryotes?



A) adding extra nucleotides to the DNA.

B) the removal of introns from the nucleotide sequence by snRNP's.

C) inducers bind with the repressor, causing a shape change and release from the operator.

D) regulatory genes make the repressor proteins that bind with the operator and prohibit the function of RNA polymerase.



Answer: B) the removal of introns from the nucleotide sequence by snRNP's.

When a trp operon is in the "off" condition,

08:17

When a trp operon is in the "off" condition,



A) the repressor will code for an operator and change shape.

B) tryptophan will bind to the repressor.

C) the binding site for tryptophan will change shape.

D) RNA Polymerase will attach to the promoter, and trytophan is produced.



Answer: B) tryptophan will bind to the repressor.

Which of the following is true about prokaryotic gene regulation?

08:17

Which of the following is true about prokaryotic gene regulation?



A) A regulator gene codes for a repressor protein that controls the operon.

B) An operator is the sequence of DNA where the RNA polymerase attaches.

C) Promoters code for enzymes and are transcribed as a unit.

D) Structural genes are located outside the operon and code for enzymes.



Answer: A) A regulator gene codes for a repressor protein that controls the operon.

Eukaryotic protein synthesis differs from that of prokaryotes because

08:17

Eukaryotic protein synthesis differs from that of prokaryotes because



A) transcription and translation occur simultaneously in eukaryotes.

B) ribosomal subunits are larger in prokaryotes.

C) operons regulate gene expression in eukaryotes.

D) related prokaryotic genes are organized into groups called operons.



Answer: D) related prokaryotic genes are organized into groups called operons.

In peas, the tall allele is dominant over the short allele. Which of the following statements is true about the cross between a homozygous dominant tall plant and a short plant, and the F1 offspring that is allowed to self-fertilize?

08:16

In peas, the tall allele is dominant over the short allele. Which of the following statements is true about the cross between a homozygous dominant tall plant and a short plant, and the F1 offspring that is allowed to self-fertilize?



A) The F2 offspring are all tall.

B) Half of the F2 offspring are short.

C) All of the F1 offspring are short.

D) Only 1/4 of the F2 offspring are short.



Answer: D) Only 1/4 of the F2 offspring are short.

A man with blood type A and a woman with blood type B have a child. If this child has type O blood, which of the following statements must be true?

08:15

A man with blood type A and a woman with blood type B have a child. If this child has type O blood, which of the following statements must be true?



A) The father could be homozygous A.

B) The mother has homozygous B blood type.

C) The maternal grandmother is homozygous A.

D) The paternal grandmother could have type O blood.



Answer: D) The paternal grandmother could have type O blood.

Paula is blood type A- and has a child who is B+; Paula requests that Bernie undergo a paternity test as a possible father of the child. If Bernie is the father, what are his possible blood types?

08:15

Paula is blood type A- and has a child who is B+; Paula requests that Bernie undergo a paternity test as a possible father of the child. If Bernie is the father, what are his possible blood types?



A) AB+ or B+

B) AB- or O+

C) A+ or B+

D) AB- or AB+


Answer: A) AB+ or B+

Which of the following statements provides the best evidence that environment can play a role in determining the phenotype of an organism?

08:15

Which of the following statements provides the best evidence that environment can play a role in determining the phenotype of an organism?



A) A primrose develops white flowers when grown above 32C, and red flowers when grown at 24C

B) The more genes involved, the more continuous is the variation in phenotypes.

C) True breeding red and white flowered four o'clocks produce pink flowered offspring at any temperature.

D) A curly haired caucasian and a straight haired caucasian will have wavy haired offspring, regardless of the time of year.



Answer: A) A primrose develops white flowers when grown above 32C, and red flowers when grown at 24C

Cystic fibrosis is an inherited autosomal recessive disease affecting the cells that produce saliva, sweat, digestive juices, and mucus. Evidence to support this particular mode of inheritance includes the fact that

08:15

Cystic fibrosis is an inherited autosomal recessive disease affecting the cells that produce saliva, sweat, digestive juices, and mucus. Evidence to support this particular mode of inheritance includes the fact that



A) Cystic fibrosis is more common in males than females.

B) Parents who are phenotypically normal can have an afflicted child.

C) Individuals with cystic fibrosis are all heterozygous.

D) females have a decreased chance of inherting cystic fibrosis due to the inactivation of the second X chromosome.



Answer: B) Parents who are phenotypically normal can have an afflicted child.

Skin color is polygenic, dependent upon many genes. Dominant alleles produce darker-pigmented skin, whereas recessive alleles produce lighter-colored skin. What is the probability that a fair skinned individual (aabbccDdEeff) and a relatively dark skinned individual (AABbCCDdeeFF) will have a child who is also relatively dark skinned with a specific genotype of (AABBccDdEeFf)?

08:14

Skin color is polygenic, dependent upon many genes. Dominant alleles produce darker-pigmented skin, whereas recessive alleles produce lighter-colored skin. What is the probability that a fair skinned individual (aabbccDdEeff) and a relatively dark skinned individual (AABbCCDdeeFF) will have a child who is also relatively dark skinned with a specific genotype of (AABBccDdEeFf)?



A) 1/64

B) 1/8

C) 1/2

D) 0



Answer: D) 0

Phenylketonuria (PKU) is an autosomal recessive disorder where afflicted individuals are incapable of metabolizing the amino acid phenylalanine, and it accumulates in nerve cells of the brain. What is the probability that a man and a woman that are both phenotypically normal, but are carriers, will have a child with PKU?

08:14

Phenylketonuria (PKU) is an autosomal recessive disorder where afflicted individuals are incapable of metabolizing the amino acid phenylalanine, and it accumulates in nerve cells of the brain. What is the probability that a man and a woman that are both phenotypically normal, but are carriers, will have a child with PKU?



A) 1/4

B) 1/2

C) 1/3

D) 1/6



Answer: A) 1/4

Which of the following provides a mechanism for genetic variation during meiosis?

08:13

Which of the following provides a mechanism for genetic variation during meiosis?



A) The unique separation of sister chromatids during the first meiotic division.

B) The presence of maternal DNA in one cell, and paternal DNA in another cell.

C) The physical exchange of regions of homologous chromosomes.

D) Two divisions create more diversity than one division.



Answer: C) The physical exchange of regions of homologous chromosomes.

Which of the following events occurs earliest in meiosis?

08:13

Which of the following events occurs earliest in meiosis?



A) Crossing over occurs between homologous chromosomes.

B) A tetrad or synaptonemal complex is formed at the equator.

C) The spindle apparatus extends outward from the centrosomes.

D) Four haploid daughter cells are formed after cytokinesis.



Answer: C) The spindle apparatus extends outward from the centrosomes.

During pregnancy, a cell undergoes what appears to be a normal mitotic nuclear division. However, two daughter cells with 2n-1 and 2n+1 complement of chromosomes are produced, causing a population of cells to be abnormal. Which of the following events is most likely responsible for this disorder?

08:12

During pregnancy, a cell undergoes what appears to be a normal mitotic nuclear division. However, two daughter cells with 2n-1 and 2n+1 complement of chromosomes are produced, causing a population of cells to be abnormal. Which of the following events is most likely responsible for this disorder?



A) Two sister chromatids did not separate into the proper daughter cells during anaphase.

B) Homologous chromosomes were sorted incorrectly during prophase.

C) The protein structure of nonkinetochore microtubules was defective, and incorrectly shortened during anaphase.

D) The cleavage furrow did not completely separate the two daughter cells.



Answer: A) Two sister chromatids did not separate into the proper daughter cells during anaphase.

Aneuploidy, defined as an abnormal number of chromosomes, is the most common chromosomal abnormality. Which of the following events will result in Down Syndrome, an example of a disorder caused by the inheritance of an extra chromosome 21?

08:12

Aneuploidy, defined as an abnormal number of chromosomes, is the most common chromosomal abnormality. Which of the following events will result in Down Syndrome, an example of a disorder caused by the inheritance of an extra chromosome 21?



A) the incorrect separation of this pair of sister chromatids during meiosis II

B) the failure of two sets of homologous chromosomes to line up properly during metaphase I

C) the nondisjunction of this set of homologues during meiosis II

D) a crossing over of genetic information of homologous chromosomes during prophase I



Answer: A) the incorrect separation of this pair of sister chromatids during meiosis II

Sexually reproducing organisms

08:12

Sexually reproducing organisms



A) depend on mutations to generate variation.

B) produce great numbers of offspring within a limited amount of time.

C) depend on crossing over during mitosis to generate genetic variation.

D) increase genetic variation due to an independent assortment of chromosomes.



Answer: D) increase genetic variation due to an independent assortment of chromosomes.

Meiosis reduces the number of chromosomes. However, this may occur at different points in the life cycles of animals, plants, and fungi. Which of the following statements is not an accurate description of these life cycles?

08:12

Meiosis reduces the number of chromosomes. However, this may occur at different points in the life cycles of animals, plants, and fungi. Which of the following statements is not an accurate description of these life cycles?



A) In animals, the haploid stage consists of only the gametes.

B) In plants, there is both a diploid and a haploid multicellular form.

C) In fungi, the dominant form is usually haploid.

D) In plants, the spore is a multicellular diploid form.



Answer: D) In plants, the spore is a multicellular diploid form.

Mitosis and meiosis are similar in that

08:11

Mitosis and meiosis are similar in that



A) the both produce haploid daughter cells.

B) sister chromatids move towards the poles in both.

C) homologous chromosomes pair and undergo crossing over in both.

D) they both contain two nuclear divisions.



Answer: B) sister chromatids move towards the poles in both.

Genetic recombination occurs due to

08:11

Genetic recombination occurs due to



A) crossing over between homologous chromosomes.

B) proper alignment of paternal chromosomes and maternal chromosomes on the proper side of the metaphase plate.

C) a differing number of homologous chromosomes in each of the daughter cells after meiosis I.

D) the production of genetically identical daughter cells after mitosis.



Answer: A) crossing over between homologous chromosomes.

Fluctuations in the amount of cell-cycle control molecules affect the rate of the cell cycle. Which of the following would slow the cell cycle?

08:11

Fluctuations in the amount of cell-cycle control molecules affect the rate of the cell cycle. Which of the following would slow the cell cycle?



A) Kinases become activated by cyclins, and inhibit mitosis.

B) Cyclins accumulate during the G1, S, and G2 phases and inhibit MPF.

C) MPF is turned off, which leads to the destruction of cyclin.

D) At the G2 checkpoint, MPF complexes form as aggregations of Cdk and cyclin.



Answer: D) At the G2 checkpoint, MPF complexes form as aggregations of Cdk and cyclin.

Which of the following is true regarding mitosis and binary fission?

08:10

Which of the following is true regarding mitosis and binary fission?



A) The duplicated DNA content of the reproducing parental cell is separated into two equal halves only in mitosis.

B) Four daughter cells consisting of a haploid compliment of chromosomes are produced in binary fission.

C) Binary fission does not separate sex chromosomes, but is able to separate autosomes.

D) Their is neither a nucleus nor centromeres in prokaryotic cells that undergo binary fission.



Answer: D) There is neither a nucleus nor centromeres in prokaryotic cells that undergo binary fission.

A major difference during cell division between plants and animals is

08:09

A major difference during cell division between plants and animals is



A) the production of a cell plate in animals and a cleavage furrow in plants.

B) centriole formation in plant cells.

C) the fusing of vesicles to form a cell wall in plants.

D) the presence of asters during spindle formation in animal cells.



Answer: D) the presence of asters during spindle formation in animal cells.

In an experiment, four sealed Erlenmeyer flasks are linked. A tube open to air is inserted into the water in flask D. Another tube connects the air in flask D to the air in flask C. A mouse is placed in flask C. A tube connects the air in flask C to the water in flask B. Another tube connects the air in flask B to the water in flask A. Another tube in flask A connects the air in flask A to an air pump. The water in flasks A, B, and D contain an indicator that will turn pink in the presence of carbon dioxide. If the mouse is carrying out cellular respiration, which of the following events will occur?

08:08

In an experiment, four sealed Erlenmeyer flasks are linked. A tube open to air is inserted into the water in flask D. Another tube connects the air in flask D to the air in flask C. A mouse is placed in flask C. A tube connects the air in flask C to the water in flask B. Another tube connects the air in flask B to the water in flask A. Another tube in flask A connects the air in flask A to an air pump. The water in flasks A, B, and D contain an indicator that will turn pink in the presence of carbon dioxide. If the mouse is carrying out cellular respiration, which of the following events will occur?



A) Flasks B and D will turn pink.

B) Only flasks A and B will turn pink.

C) Only flask D will turn pink.

D) None of the flasks will turn pink.



Answer: B) Only flasks A and B will turn pink.

Which of the following statements is true regarding cellular respiration?

08:07

Which of the following statements is true regarding cellular respiration?



A) Anaerobic respiration requires oxygen in order to generate ATP.

B) The citric acid cycle produces NADPH, which releases energy to fuel chemiosmosis.

C) Oxygen is formed as water combines with electrons at the end of an electron transport chain.

D) Glucose is broken down into two pyruvate molecules during glycolysis.



Answer: D) Glucose is broken down into two pyruvate molecules during glycolysis.

Which of the following events occurs first during chemiosmosis?

08:07

Which of the following events occurs first during chemiosmosis?



A) integral proteins translocate H+ ions across the membrane, creating a pH gradient.

B) ATP synthase molecules facilitate the movement of H+ ions across the membrane.

C) ATP synthase phosphorylates ADP.

D) the electrons are taken up by oxygen to make water.



Answer: A) integral proteins translocate H+ ions across the membrane, creating a pH gradient.

Trematol is a poison that inhibits the breakdown of lactic acid. How could strenuous exercise produce effects that could be confused with trematol poisoning?

04:07

Trematol is a poison that inhibits the breakdown of lactic acid. How could strenuous exercise produce effects that could be confused with trematol poisoning?



A) Both cause a decrease in acidity due to the accumulation of lactic acid.

B) Both lead to the lack of lactate dehydrogenase to break down pyruvate.

C) Trematol inhibits the conversion of pyruvate to glucose, leading to an insufficiency of ATP.

D) Lactic acid is produced anaerobically during strenuous exercise, and will accumulate in the muscles in both situations.



Answer: D) Lactic acid is produced anaerobically during strenuous exercise, and will accumulate in the muscles in both situations.

Glycolysis can be described as a process that

04:07

Glycolysis can be described as a process that



A) is aerobic and produces 2 ATP per glucose molecule

B) converts glucose to pyruvate

C) yields 34 ATP molecules through the process of chemiosmosis

D) produces O2 as a by-product



Answer: B) converts glucose to pyruvate

At constant temperature,

03:05

At constant temperature,



A) the rate of photosynthesis will vary with light intensity.

B) the higher the irradiance, the higher the rate of photosynthesis.

C) the rate of photosynthesis decreases with an increase in atmospheric carbon dioxide.

D) the rate of photosynthesis is unaffected by water availability.



Answer: A) the rate of photosynthesis will vary with light intensity.

In the fall, the leaves of many trees change from green to red or yellow. Which of the following statements explains this observation?

03:03

In the fall, the leaves of many trees change from green to red or yellow. Which of the following statements explains this observation?



A) Leaves produce more chlorophyll as temperatures drop.

B) Carotenes and Xanthophylls are produced only in the fall, when leaves turn yellow or orange.

C) The chlorophyll breaks down, and the accessory pigments are more noticable.

D) Reduced amounts of sunlight reflect less green light, making it easier to see than other pigments.



Answer: C) The chlorophyll breaks down, and the accessory pigments are more noticable.

During the light dependent reactions,

03:03

During the light dependent reactions,



A) carbon dioxide is fixed into sugar.

B) the hydrolysis of water supplies electrons to photosystem II.

C) ATP is broken down into ADP and P.

D) NADPH+ is broken down into NADP and H.



Answer: B) the hydrolysis of water supplies electrons to photosystem II.

Oxygen is produced when

03:02

Oxygen is produced when



A) electrons are accepted by water at the end of photosystem II.

B) water is split at the initiation of photosystem II.

C) protons from water are used in the production of carbohydrates in the stroma.

D) CO2 is oxidized, and carbon is utilized in the production of carbohydrates.



Answer: B) water is split at the initiation of photosystem II.

RuBP carboxylase (Rubisco)

03:02

RuBP carboxylase (Rubisco)



A) captures CO2 from the atmosphere and converts it to two 3-carbon sugars.

B) transports H+ across the chloroplast membrane in chemiosmosis.

C) combines with CO2 to form oxaloacetate in C4 photosynthesis.

D) releases a molecule of CO2 as it is converted to pyruvate.



Answer: A) captures CO2 from the atmosphere and converts it to two 3-carbon sugars.

Evidence that crabgrass, corn, and sugar cane (C4 plants) are adapted to higher temperatures would be

03:02

Evidence that crabgrass, corn, and sugar cane (C4 plants) are adapted to higher temperatures would be



A) CO2 is obtained during the day and incorporated into a 3-carbon compound.

B) They require fewer enzymes, and have no specialized anatomy.

C) avoiding photorespiration by converting CO2 to an acid and storing it during the night, and converting it back into CO2 during the daytime.

D) avoidance of photorespiration by first incorporating CO2 into a 4-carbon compound and then translocating it into bundle sheath cells.



Answer: D) avoidance of photorespiration by first incorporating CO2 into a 4-carbon compound and then translocating it into bundle sheath cells.


The light dependent reactions of photosynthesis

03:01

The light dependent reactions of photosynthesis



A) occur in the stroma of the chloroplasts.

B) occur when hydrogen and carbon dioxide react to form a carbohydrate.

C) release oxygen as a by-product and split water in the process.

D) utilize NAD+ as an electron acceptor.



Answer: C) release oxygen as a by-product and split water in the process.

Increasing substrate concentration will

03:01

Increasing substrate concentration will



A) result in an increased rate of reaction until there is no substrate left.

B) not affect the rate of the reaction.

C) result in a decreased rate of reaction because there will be a higher percentage of substrate molecules.

D) initially result in a decreased rate of reaction, but will then increase toward the end of the reaction period.



Answer: A) result in an increased rate of reaction until there is no substrate left.

Which of the following statements is true regarding enzymatic reactions?

02:48

Which of the following statements is true regarding enzymatic reactions?



A) Endergonic reactions can be accelerated by coupling them to an exergonic reaction.

B) Reactants contain less energy than products in exergonic reactions.

C) Enzymes increase the activation energy necessary for a reaction to proceed.

D) Competitive inhibitors bond with an enzyme outside of the active site.



Answer: A) Endergonic reactions can be accelerated by coupling them to an exergonic reaction.

The reduction of carbon dioxide to a carbohydrate

02:47

The reduction of carbon dioxide to a carbohydrate



A) utilizes energy captured in photosynthesis.

B) occurs in the mitochondria.

C) is an exergonic reaction.

D) occurs during aerobic respiration.



Answer: A) utilizes energy captured in photosynthesis.

Which of the following is true regarding the transport of molecules?

02:45

Which of the following is true regarding the transport of molecules?



A) Facilitated diffusion transports molecules against the concentration gradient, and requires energy to do so.

B) Active transport transports small molecules with the concentration gradient in large quantities, but does not require energy.

C) Receptor-mediated endocytosis makes use of receptor proteins, and transports solids or liquids with the help of lysosomes into the cell.

D) Osmosis is an active transport process that moves water against the concentration gradient.



Answer: C) Receptor-mediated endocytosis makes use of receptor proteins, and transports solids or liquids with the help of lysosomes into the cell.

Many fields require heavy irrigation, and in desert areas, much of that water evaporates, leaving behind solutes. This may cause plant cells

02:44

Many fields require heavy irrigation, and in desert areas, much of that water evaporates, leaving behind solutes. This may cause plant cells



A) to become turgid due to the increase in solute in the surrounding environment.

B) to lose water to the surrounding hypotonic environment.

C) to grow excessively, due to the increased N-P-K fertilizer in the soil.

D) to plasmolysize, due to osmosis of water to a lower water potential.



Answer: D) to plasmolysize, due to osmosis of water to a lower water potential.

Plant cells placed in a hypotonic environment

02:44

Plant cells placed in a hypotonic environment



A) will lyse without special adaptations to combat water concentration fluctuations.

B) will remain flaccid, due to an ineffective central vacuole.

C) will remain turgid, due to the elastic cell wall.

D) will shrivel, due to the loss of water from the large central vacuole.



Answer: C) will remain turgid, due to the elastic cell wall.

The rate of diffusion can be increased by

02:43

The rate of diffusion can be increased by



A) increasing the temperature.

B) decreasing pressure.

C) increasing the size of the molecules.

D) decreasing concentration.



Answer: A) increasing the temperature.

An artificial cell consisting of an aqueous solution with 0.5 M sucrose and 0.2 M glucose that is permeable only two monosaccharides is placed in a beaker of water containing 0.2 M sucrose and 0.1 M glucose. Which of the following will occur?

02:42

An artificial cell consisting of an aqueous solution with 0.5 M sucrose and 0.2 M glucose that is permeable only two monosaccharides is placed in a beaker of water containing 0.2 M sucrose and 0.1 M glucose. Which of the following will occur?



A) The net movement of water will be out of the cell.

B) Sucrose will move out of the cell, and glucose will move into the cell.

C) There will be no net movement of water.

D) Glucose will move out of the cell.



Answer: D ) Glucose will move out of the cell.

Which of the following observations could lead researchers to conclude that membrane proteins move laterally in the plasma membrane?

02:42

Which of the following observations could lead researchers to conclude that membrane proteins move laterally in the plasma membrane?



A) A cell is freeze-fractured and splits the phospholipid bilayer into two layers, and the membrane proteins go with one of the layers.

B) Human and mouse sauce labeled with protein markers are fused, and the hybrid cell contains a mixing of proteins on the surface.

C) There are two types of protein receptors in plants to transport CO2 and NH4-; however, in some microorganisms, proteins that transport NH4 can also transport CO2.

D) Integral proteins on the surface of stomach cells can transport either acids or bases.



Answer: B) Human and mouse sauce labeled with protein markers are fused, and the hybrid cell contains a mixing of proteins on the surface.

Which of the following examples is a specific case of active transport?

02:41

Which of the following examples is a specific case of active transport?



A) A carrier proteins moves sucrose across the membrane with the concentration gradient.

B) cytoplasmic Na+ mines to the sodium potassium pump, ATP is used, and NA+ is released to the outside.

C) water moves from an area of high free-water concentration to an area of low free-water concentration.

D) Aquaporins facilitate the diffusion of water in the red blood cells of mammals.



Answer: B) cytoplasmic Na+ mines to the sodium potassium pump, ATP is used, and NA+ is released to the outside.

Several diseases, including Tay-Sachs and Pompe's disease, are caused by the absence of one or more enzymes to break down biomolecules, such as lipids and proteins. Which of the following organelles is most likely dysfunctional in these diseases?

02:39

Several diseases, including Tay-Sachs and Pompe's disease, are caused by the absence of one or more enzymes to break down biomolecules, such as lipids and proteins. Which of the following organelles is most likely dysfunctional in these diseases?



A) cell wall

B) cytoskeleton

C) chloroplast

D) lysosome



Answer: D) lysosome

produces ATP for cellular energy

02:38

produces ATP for cellular energy



A) Mitochondria

B) Smooth endoplasmic reticulum

C) Chloroplast

D) Lysosome



Answer: A) Mitochondria

converts CO2 and H2O to glucose

02:37

converts CO2 and H2O to glucose



A) Mitochondria

B) Smooth endoplasmic reticulum

C) Chloroplast

D) Lysosome



Answer: C) Chloroplast

Evidence supporting the fact that an increase in the amount of surface area directly increases the efficiency of cellular processes would NOT be shown by which of these?

02:37

Evidence supporting the fact that an increase in the amount of surface area directly increases the efficiency of cellular processes would NOT be shown by which of these?



A) Mitochondria contain many folds called cristae.

B) Chloroplasts contain stacks of thylakoids.

C) Microvilli (very small folds) are present on cells of the small intestine.

D) The large central vacuole maintains pH and allows enzymes to act.



Answer: D) The large central vacuole maintains pH and allows enzymes to act.

Your biology teacher shows you an electron micrograph image of a cell that contains DNA, ribosomes, and leucoplasts, and it has a cell wall. Which of the following types of organisms contains this cell?

02:37

Your biology teacher shows you an electron micrograph image of a cell that contains DNA, ribosomes, and leucoplasts, and it has a cell wall. Which of the following types of organisms contains this cell?



A) red pine

B) Streptococcus

C) C. amoeba

D) mushroom



Answer: A) red pine

Tay-Sachs disease often affects children by progressively destroying cells in their brains due to the accumulation of a specific type of fat. This is due to the fact that

02:37

Tay-Sachs disease often affects children by progressively destroying cells in their brains due to the accumulation of a specific type of fat. This is due to the fact that



A) the Golgi bodies do not transport fats out of the cell in vesicles, and they accumulate in the cell.

B) the lysosomes do not contain the appropriate enzyme to metabolize the fat.

C) the fats are not permeable to the cell wall and they accumulate in the cell.

D) hydrogen peroxide is not produced by the peroxisomes to destroy the fats.



Answer: B ) the lysosomes do not contain the appropriate enzyme to metabolize the fat.

Ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) differ structurally in that

02:34

Ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) differ structurally in that



A) DNA is single-stranded, and RNA is double-stranded.

B) DNA contains uracil.

C) RNA bonds purines to purines, and DNA bonds pyrimidines to pyrimidines.

D) DNA contains deoxyribose, and RNA does not.



Answer: D) DNA contains deoxyribose, and RNA does not.

Which of the following statements is true regarding chaperone proteins?

02:33

Which of the following statements is true regarding chaperone proteins?



A) they specify the correct structure of a polypeptide

B) they are carbohydrates that bond with proteins to maintain proper shape

C) they are organic molecules that protect against disease

D) they are protein molecules that assist in the proper folding of other proteins



Answer: D) they are protein molecules that assist in the proper folding of other proteins

A dehydration reaction in the synthesis of a fat

02:32

A dehydration reaction in the synthesis of a fat



A) creates glycostatic linkages between the glycerol and the fatty acids.

B) removes one molecule of water for each fatty acid joined to the glycerol.

C) bonds water to the glycerol molecule to form a triacylglycerol.

D) requires water to form peptide bonds.



Answer: B) removes one molecule of water for each fatty acid joined to the glycerol.

Hydrocarbons do not vary in

02:31

Hydrocarbons do not vary in



A) length.

B) branching.

C) bonding patterns.

D) composition.



Answer: D) composition.

Which of the following atoms has four electrons available for covalent bonding, and can form rings, long chains, and double bonds, making it the building block of the most versatile complex biological molecules?

02:31

Which of the following atoms has four electrons available for covalent bonding, and can form rings, long chains, and double bonds, making it the building block of the most versatile complex biological molecules?



A) Carbon

B) Silicon

C) Hydrogen

D) Oxygen



Answer: A) Carbon

If you place the corner of a paper towel into a droplet of water, the water moves across the paper towel. Which of the following would best explain the movement of the water?

02:29

If you place the corner of a paper towel into a droplet of water, the water moves across the paper towel. Which of the following would best explain the movement of the water?



A) Surface tension allows molecules to form a bubble within the fibers of the paper towel and be absorbed.

B) Cohesion between the polar ends of the water molecules and the carbons in the paper towels allow water to be absorbed.

C) Cohesion of the water molecules to other water molecules from a chain that is absorbed by the paper towel.

D) Ionic bonding between the water and the paper towel allow water to be absorbed.



Answer: C) Cohesion of the water molecules to other water molecules from a chain that is absorbed by the paper towel.

If water had a low heat capacity,

02:28

If water had a low heat capacity,



A) temperature changes would require a great deal of energy input.

B) the water in organisms would heat quickly and cause the cells to burst.

C) the water in lakes would evaporate on a hot day.

D) ectothermic animals would be more adapted to their surroundings.



Answer: B) the water in organisms would heat quickly and cause the cells to burst.

Why is it important that hydrogen ions in two different water molecules would be attracted to one another or that the oxygen atoms in two water molecules would repel one another?

02:28

Why is it important that hydrogen ions in two different water molecules would be attracted to one another or that the oxygen atoms in two water molecules would repel one another?



A) hydrogen atoms have a partial negative charge, and will be attracted to one another.

B) the slightly positive hydrogen of one molecule is attracted to the slightly negative oxygen of another molecule.

C) hydrogen is more electronegative than oxygen, and the electrons spend more time closer to the oxygen atom.

D) its tow hydrogen atoms are joined to the oxygen atom by single covalent bonds.



Answer: B) the slightly positive hydrogen of one molecule is attracted to the slightly negative oxygen of another molecule.

A buffer works by

02:28

A buffer works by



A) accepting hydrogen ions from the solution when they are in excess.

B) irreversibly combining with hydrogen ions to neutralize a base.

C) dissociating to yield OH- ions to neutralize an acid.

D) donating hydrogen ions when they are in excess.



Answer: A) accepting hydrogen ions from the solution when they are in excess.

Ionic bonds involve the

02:27

Ionic bonds involve the



A) equal sharing of electrons.

B) transfer of electrons.

C) uneven sharing of electrons.

D) asymmetric distribution in molecules.



Answer: B) transfer of electrons.

Hydrogen bonds and ionic bonds are weak interactions. Therefore,

02:27

Hydrogen bonds and ionic bonds are weak interactions. Therefore,



A) their cumulative effects reinforce molecular structure, making them biologically significant.

B) they are not found in organic molecules.

C) they occur between molecules that are far apart.

D) they occur when two atoms are equally electronegative and are attracted to one another.



Answer: A) their cumulative effects reinforce molecular structure, making them biologically significant.

In a molecule of DNA, the bonds holding the side chains must be strong, whereas the bonds holding the rungs of the ladder between the nucleic acids must break during DNA replication. What types of bonds are most likely present between adenine and thymine and cytosine and guanine in a DNA molecule?

02:27

In a molecule of DNA, the bonds holding the side chains must be strong, whereas the bonds holding the rungs of the ladder between the nucleic acids must break during DNA replication. What types of bonds are most likely present between adenine and thymine and cytosine and guanine in a DNA molecule?



A) nonpolar covalent

B) ionic

C) polar covalent

D) hydrogen



Answer: D) hydrogen

Which of the following statements is not true regarding the properties of water?

02:26

Which of the following statements is not true regarding the properties of water?



A) Hydrogen bonds require less energy to break than do covalent bonds.

B) Water cools more slowly than other liquids.

C) The hydrogen bonds between water hold more heat energy than most other liquids.

D) Water's surface tension is due to hydrogen bonds between water molecules.



Answer: C) The hydrogen bonds between water hold more heat energy than most other liquids.

If the student were to revise this experiment, which of the following modifications would improve the experimental design of the investigation?

02:24

A student set up an experiment using Drosophila melanogaster. The student wished to determine the LC-50 dose of caffeine exposure to this particular species of fruit flies. The lethal concentration is reached when 50% (LC-50) or more of the flies die when exposed to a toxin. The student mixed various concentrations of caffeine with the fruit fly media, added 50 eggs to each vial, and waited one week to analyze the results. Below are the results of the study. PICTURE


If the student were to revise this experiment, which of the following modifications would improve the experimental design of the investigation?


A) The student should run additional trials at each level of exposure.

B) The student should place additional eggs in each vial.

C) The student should use higher concentrations of caffeine.

D) The student should compare results with eggs of another insect.



Answer: A) The student should run additional trials at each level of exposure.

Over time, one group of squirrels become separated from another group. Due to erosion and the subsequent formation of a river, the squirrels are unable to cross. The geographic barrier prevents breeding between the two groups of squirrels. Which term could be used to describe each group of squirrels?

02:24

Over time, one group of squirrels become separated from another group. Due to erosion and the subsequent formation of a river, the squirrels are unable to cross. The geographic barrier prevents breeding between the two groups of squirrels. Which term could be used to describe each group of squirrels?



A) Population

B) Ecosystem

C) Community

D) Species



Answer: A) Population

Genetic variation _____.

02:13

Genetic variation _____.


a. is created by the direct action of natural selection

b. tends to be reduced by when diploid organisms produce gametes

c. must be present in a population before natural selection can act upon the population

d. arises in response to changes in the environment



Answer: C

Three-spined stickleback fish (Gasterosteus aculeatus) show substantial heritable variation in gill-raker length related to differences in their diets. Longer gill rakers appear to function better for capturing open-water prey, while shorter gill rakers function better for capturing shallow-water prey. Which of the following types of selection is most likely to be found in a large lake (open water in the middle and shallow water around the sides) with a high density of these fish?

02:12

Three-spined stickleback fish (Gasterosteus aculeatus) show substantial heritable variation in gill-raker length related to differences in their diets. Longer gill rakers appear to function better for capturing open-water prey, while shorter gill rakers function better for capturing shallow-water prey. Which of the following types of selection is most likely to be found in a large lake (open water in the middle and shallow water around the sides) with a high density of these fish?



a. stabilizing selection

b. directional selection

c. sexual selection

d. disruptive selection



Answer: D

When imbalances occur in the sex ratio of sexual species that have two sexes (that is, other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of _____.

02:12

When imbalances occur in the sex ratio of sexual species that have two sexes (that is, other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of _____.



a. sexual selection

b. frequency-dependent selection

c. stabilizing selection

d. balancing selection

e. disruptive selection



Answer: B

The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid-1700s. They do not marry with members outside their own immediate community. Today, the Dunkers are genetically unique and differ in gene frequencies, at many loci, from all other populations including those in their original homeland. Which of the following likely explains the genetic uniqueness of this population?

02:12

The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid-1700s. They do not marry with members outside their own immediate community. Today, the Dunkers are genetically unique and differ in gene frequencies, at many loci, from all other populations including those in their original homeland. Which of the following likely explains the genetic uniqueness of this population?




a. heterozygote advantage and stabilizing selection

b. population bottleneck and Hardy-Weinberg equilibrium

c. mutation and natural selection

d. founder effect and genetic drift

e. sexual selection and inbreeding depression



Answer: D

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. The actual forelimbs of these mammals do not seem to be optimally arranged because _____.

01:43

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. The actual forelimbs of these mammals do not seem to be optimally arranged because _____.



a. natural selection has not had sufficient time to create the optimal design in each case, but will do so given enough time

b. in many cases, phenotype is determined by genotype and the environment

c. though we may not consider the fit between the current skeletal arrangements and their functions excellent, we should not doubt that natural selection ultimately produces the best design

d. natural selection is generally limited to modifying structures that were present in previous generations and in previous species



Answer: D

Two frog populations (same species) living in two neighboring lakes sing slightly different courtship songs. Increased irrigation makes the land between the two lakes wetter, allowing frogs to expand their ranges to the area between the lakes. Females in both populations prefer loud frogs to quieter frogs, but do not distinguish between the two slightly different songs. Assuming that courtship song differences have a genetic basis, predict what will likely happen to the songs of the two frog populations.

01:42

Two frog populations (same species) living in two neighboring lakes sing slightly different courtship songs. Increased irrigation makes the land between the two lakes wetter, allowing frogs to expand their ranges to the area between the lakes. Females in both populations prefer loud frogs to quieter frogs, but do not distinguish between the two slightly different songs. Assuming that courtship song differences have a genetic basis, predict what will likely happen to the songs of the two frog populations.



a. You cannot predict a change in the courtship songs at the two lakes.

b. Genetic drift will cause the songs to differentiate even more.

c. The songs will become more similar to each other.

d. Males will become louder.

e. Disruptive selection will cause the songs to differentiate even more.



Answer: C

Genetic drift occurs in a population. Which of the following statements might be true?

01:42

Genetic drift occurs in a population. Which of the following statements might be true?



a. Genetic drift decreased the population's fitness.

b. Genetic drift increased the population's fitness.

c. The population was relatively small.

d. Any of the statements can be true.

e. The population experiences a decrease in genetic variation.



Answer: D

Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer or more than this have reduced fitness. Which of the following terms best describes this situation?

01:14

Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer or more than this have reduced fitness. Which of the following terms best describes this situation?



a. stabilizing selection

b. disruptive selection

c. sexual selection

d. directional selection

e. artificial selection



Answer: A

Over long periods of time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

01:13

Over long periods of time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?



a. Natural selection cannot account for losses, but accounts only for new structures and functions.

b. Natural selection accounts for these losses by the principle of use and disuse.

c. Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits.

d. The ancestors of these organisms experienced harmful mutations that forced them to lose these structures.



Answer: C

Which of the following is a fitness trade-off (compromise)?

01:13

Which of the following is a fitness trade-off (compromise)?



a. Hummingbirds are the best pollinators of certain flowers, but bees are the best pollinators for orchids.

b. The strong, thick beak of a woodpecker helps it find insects in trees.

c. In some hornbill species, the male helps seal the female in a tree with her nest until the young are ready to fledge.

d. Turtle shells provide protection but are heavy and burdensome when moving.



Answer: D

Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, it is possible for genes from bird flu virus and human flu virus to be combined. If the human flu virus contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug) to the new virus, and if the new virus is introduced to an environment lacking Tamiflu, then what is most likely to occur?

01:11

Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, it is possible for genes from bird flu virus and human flu virus to be combined. If the human flu virus contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug) to the new virus, and if the new virus is introduced to an environment lacking Tamiflu, then what is most likely to occur?


a. The Tamiflu-resistance gene will undergo mutations that convert it into a gene that has a useful function in this environment.

b. If the Tamiflu-resistance gene involves a cost, it will experience directional selection leading to reduction in its frequency.

c. If the Tamiflu-resistance gene confers no benefit in the current environment, and has no cost, the virus will increase in frequency.

d. The new virus will maintain its Tamiflu-resistance gene, in case of future exposure to Tamiflu.



Answer: B

Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 9 in 10,000 newborn babies have the disease, what are the expected frequencies of the dominant (A1) and recessive (A2) alleles according to the Hardy-Weinberg model?

01:11

Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 9 in 10,000 newborn babies have the disease, what are the expected frequencies of the dominant (A1) and recessive (A2) alleles according to the Hardy-Weinberg model?


a. f(A1) = 0.9700, f(A2) = 0.0300

b. f(A1) = 0.9997, f(A2) = 0.0003

c. f(A1) = 0.9600, f(A2) = 0.0400

d. f(A1) = 0.9800, f(A2) = 0.0200

e. f(A1) = 0.9604, f(A2) = 0.0392



Answer: A

Mutation is the only evolutionary mechanism that _____.

01:08

Mutation is the only evolutionary mechanism that _____.



a. is more important in eukaryotes than in prokaryotes

b. decreases fitness

c. happens in all populations

d. does little to change allele frequencies

e. has no effect on genetic variation



Answer: D

A researcher wants to know if gene flow is contributing to evolution of drought tolerance of pitcher plants in a specific bog. As a control, she should

01:08

A researcher wants to know if gene flow is contributing to evolution of drought tolerance of pitcher plants in a specific bog. As a control, she should



a. Estimate the frequency of alleles relevant genes for drought tolerance.

b. None of these. Gene flow does not contribute to evolution.

c. All of the above.

d. Determine if the population is in Hardy-Weinberg equilibrium.

e. Transplant pitcher plants from other populations into the bog.



Answer: D

Natural selection _____.

01:08

Natural selection _____.


a. can favor beneficial mutations

b. does not affect harmful mutations

c. is a random process

d. creates beneficial mutations



Answer: A

In 1986, a nuclear power accident in Chernobyl, USSR (now Ukraine), led to high radiation levels for miles surrounding the plant. The high levels of radiation caused elevated mutation rates in the surviving organisms, and evolutionary biologists have been studying rodent populations in the Chernobyl area ever since. Based on your understanding of evolutionary mechanisms, which of the following most likely occurred in the rodent populations following the accident?

01:07

In 1986, a nuclear power accident in Chernobyl, USSR (now Ukraine), led to high radiation levels for miles surrounding the plant. The high levels of radiation caused elevated mutation rates in the surviving organisms, and evolutionary biologists have been studying rodent populations in the Chernobyl area ever since. Based on your understanding of evolutionary mechanisms, which of the following most likely occurred in the rodent populations following the accident?



a. Mutation caused genetic drift and decreased fitness.

b. Mutation caused the fixation of new alleles.

c. Mutations caused major changes in rodent physiology over time.

d. Mutation led to increased genetic variation.



Answer: D

In the Hardy-Weinberg equation, 2pq equals the percentage of _____.

01:07

In the Hardy-Weinberg equation, 2pq equals the percentage of _____.



a. frequency of dominant allele

b. expected frequency of homozygous dominant genotypes

c. expected frequency of homozygous recessive genotypes

d. frequency of recessive allele

e. expected frequency of heterozygous genotypes



Answer: E

Chromosome-level mutations can:

01:02

Chromosome-level mutations can:



A) duplicate an existing allele

B) lead to deletion and loss of an allele

C) guarantee that duplicated alleles are going to be different from each other

D) A & B

E) A, B & C



Answer: D

Which of the following is a fitness trade-off (compromise)?

01:00

Which of the following is a fitness trade-off (compromise)?



a. Hummingbirds are the best pollinators of certain flowers, but bees are the best pollinators for orchids.

b. The strong, thick beak of a woodpecker helps it find insects in trees.

c. In some hornbill species, the male helps seal the female in a tree with her nest until the young are ready to fledge.

d. Turtle shells provide protection but are heavy and burdensome when moving.



Answer: D

In order to have a year-round supply of cut flowers, such as Tulips and Crocus, that grow from bulbs; greenhouse growers are known to __________ bulbs. This means they plant bulbs out of season and grow them in a cold or refrigerated area for 10-12 weeks.

00:45

In order to have a year-round supply of cut flowers, such as Tulips and Crocus, that grow from bulbs; greenhouse growers are known to __________ bulbs. This means they plant bulbs out of season and grow them in a cold or refrigerated area for 10-12 weeks.



A. Force

B. Fertilize

C. Prune

D. Divide



Answer: A. Force

The amount of light a plant receives greatly influences root growth, shoot growth, and flowering. The highest quality greenhouse plants need ______________ foot candles of light per day?

00:15

The amount of light a plant receives greatly influences root growth, shoot growth, and flowering. The highest quality greenhouse plants need ______________ foot candles of light per day?



A. 500-1,000

B. 2,000-3,000

C. 4,000-6,000

D. 7,000-8,000



Answer: C. 4,000-6,000

In a horticulture business, the product you choose to produce and retail should be at what price above the total production and marketing costs (all fixed and variable costs) to make it feasible to produce and sell?

00:14

In a horticulture business, the product you choose to produce and retail should be at what price above the total production and marketing costs (all fixed and variable costs) to make it feasible to produce and sell?



A. 100%

B. 150%

C. 250%

D. 500%



Answer: C. 250%

Clogged stems in cut flowers are caused by an air embolism. An air embolism is

00:09

Clogged stems in cut flowers are caused by an air embolism. An air embolism is



A. Where disease organisms move into the flower from the air clogging the stem.

B. Where a bubble of air enters the xylem preventing water from reaching the flower.

C. Where the different between room and flower cooler temperature clog the stem.

D. Where the flower stem clogs when the flower cooler temperature drops below 36 degrees F.



Answer: B. Where a bubble of air enters the xylem preventing water from reaching the flower.

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