Purdue Bio 111 Lab Exam #2

1. In the properties of enzymes lab, which of the following represents a manipulated (independent) variable?

A. Initial rate of reaction.

B. Maximum reaction velocity.

C. Km.

D. Change in absorbance over time.

E. pH.

E.

2. What happens to initial reaction rate if enzyme concentration is tripled? (Assume conditions like those in the properties of enzymes lab, and assume that the pH and initial substrate concentration are constant.)

A. The initial rate will increase by a factor of 9 because the rate is dependent on the square of the enzyme concentration.

B. The initial rate will triple when enzyme concentration is tripled because the initial rate of reaction is linearly related to enzyme concentration.

C. The fixed substrate concentration will hold the initial rate constant because only substrate concentration governs the reaction rate.

D. The fixed pH will hold the initial rate constant because only pH governs the reaction rate.

E. The initial rate will not change because the enzyme is saturated with substrate.

b.

3. Which of the following best describes the relationship between initial reaction rate and initial substrate concentration?

A. As the initial substrate concentration increases, the initial rate of reaction also increases up to a point, and then the initial rate becomes constant.

B. As the initial substrate concentration increases, the initial rate of reaction decreases down to a point, then the initial rate becomes constant.

C. As initial substrate concentration increases, the initial rate of reaction decreases.

D. As initial substrate concentration increases, the initial rate of reaction remains constant because only pH governs initial reaction rate.

E. As initial substrate concentration increases, the initial rate of reaction increases.

A

4. In the enzyme lab, the Spec 20 you used was set to 405 nm. Why was this so?

A. 405 nm is an absorbance peak of pNPP.

B. 405 nm is an absorbance peak of alkaline phosphatase.

C. 405 nm is an absorbance peak of phosphate ion.

D. 405 nm is an absorbance peak of para-nitrophenol.

E. 405 nm is an absorbance peak of the buffer used to hold the pH steady.

D

5. Consider the corn plants represented by the diagrams. The "d" (height) and "rg" (leaf margin) loci are both on chromosome #3. If crossing-over does occur, which of the following is true?

A. The homozygous parent produces four different gene combinations in its gametes.

B. The heterozygous parent produces four different gene combinations in its gametes.

C. The heterozygous parent produces only two different gene combinations in its gametes.

D. The gametes of the heterozygous parent each contain 2 height and 2 leaf margin alleles.

E. The gametes of the homozygous parent each contain 2 height, but no leaf margin alleles.

B

6. Which of the following is true of a genetic test cross?

A. Both parents must be homozygous recessive for the gene pairs of interest.

B. One parent must be homozygous recessive for the gene pairs of interest.

C. Both parents must be heterozygous for the gene pairs of interest.

D. One parent must be homozygous dominant for the gene pairs of interest.

E. Both parents must be homozygous dominant for the gene pairs of interest.

B

7. Linked on chromosome #2 in Drosophila are genes for eye color and wing type. The recessive eye color allele (pr) leads to purple eyes, whereas the dominant allele (pr+) causes the wild type eye color. At the other locus, the vestigial wing allele (vg) is recessive to the normal wing gene (vg+). A cross between a fly heterozygous at both loci and a fly homozygous recessive at both loci was performed. The following table shows the results of the cross. (2000 offspring total.)

As a minimum estimate, how far apart are the these genes on chromosome #2?

A. Approximately 10 map units

B. Approximately 20 map units

C. Approximately 80 map units

D. Approximately 90 map unitsE. It cannot be determined because this is not a test cross.

A

9. Which of the following is/are included in the biochemical consequences of egg activation?

A. Increase in DNA synthesis.

B. Increase in RNA synthesis

C. Increase in protein synthesis.

D. All the above are consequences of egg activation.

E. Only A and C are consequences of egg activation, because the egg contains no RNA before activation.

D

10. Which of the following is/are indicator(s) of animal-vegetal polarity in eggs?

A. The distribution of pigment in the egg.

B. The distribution of yolk in the egg.

C. The location of the nucleus in the egg.

D. All of the above are valid indicators of animal-vegetal polarity in eggs.

E. Only B and C above are valid indicators of animal-vegetal polarity in eggs.

D

11. How does cleavage differ between frog zygotes and chicken zygotes?

A. The vast amount of yolk in the frog vegetal hemisphere entirely prevents cleavage in that hemisphere; in chickens the small amount of yolk in the vegetal hemisphere does not impede cleavage.

B. Cleavage occurs throughout the cytoplasm of the frog zygotes, in both animal and vegetal hemispheres; in chickens cleavage is restricted to the animal hemisphere.

C. In frogs cleavage produces cells that are smaller in the animal hemisphere than in the vegetal hemisphere; in chickens the opposite is true.

D. In frogs cleavage begins after fertilization; in chickens cleavage is well underway before fertilization.

E. In frogs cleavage occurs only horizontally; in chickens it is only vertical.

B

12. Which of the following do the blastulas of the sea urchin, frog and chicken embryos hold in common?

A. Presence of well-developed somites.

B. Presence of a cavity called the blastocoel.

C. Formation of a blastodisc at the animal pole of the egg.

D. Movement of the blastoderm into the blastocyst cavity to form the endoderm.

E. Movement of the blastoderm under the primitive streak.

B

13. Which of the following is/are true of polyspermy?

A. Polyspermy always leads to normal development.

B. Polyspermy is very likely if the concentration of sperm near the egg is low.

C. Polyspermy may occur if the fertilization membrane fails to form.

D. Polyspermy is caused by a rapid change in the electrical potential of the egg cell membrane that is in turn caused by the fusion of an egg and sperm.

E. All the above are true of polyspermy.

C

14. Which of the following show(s) holoblastic cleavage?

A. Mammal zygotes

B. Amphibian zygotes

C. Chicken zygotes

D. Echinoderm zygotes

E. All of the above, except C, show holoblastic cleavage.

E

15. Cleavage in early mammalian embryos is most like the cleavage in which of the following?

A. early echinoderm embryos

B. early amphibian embryos

C. early bird embryos

D. Cleavage in early mammal embryos is not remotely similar to any of the organisms listed above.

E. Cleavage in early mammal embryos is exactly like cleavage in all of the organisms listed above.

A

16. Which of the following is true of the first three cleavages in echinoderm development?

A. All three cleavages are vertical, from animal pole to vegetal pole.

B. The first two cleavages are vertical, the third is horizontal.

C. The first three cleavages produce the archenteron of the embryo.

D. The first three cleavages produce the vegetal plate of the embryo.

E. The first two cleavages are horizontal, the third is vertical.

B

17. Which of the following occur(s) during sea urchin development?

A. Formation of the mouth from the blastopore.

B. The archenteron developing from an inward buckling of the vegetal plate.

C. Formation of a fertilization membrane.

D. All the above are observed in sea urchin development.

E. Only B and C are observed in sea urchin development.

E

What is the purpose of the fertilization membrane?

The fertilization membrane is one mechanism that prevents polyspermy (the entrance of more than one sperm into the egg)

It is a long term mechanical barrier that helps ensure the zygote will be diploid and not triploïdies or tetraploid or whatever

The membrane provides long term protection but it takes about a minute to be deployed

What occurs while the fertilization membrane is being constructed?

A rapid short term electrical block to polyspermy protects the just-fertilized egg

What two things does fertilization accomplish?

1. Activates the oocyte (sometimes the egg) so that it goes on to complete its development

2. Provides he means by which a haploid set of chromosomes of the sperm joins the haploid set of chromosomes of the egg. This restores the diploid condition and makes a brand new unique combination of genes in the individual from the zygote that is created