BIOL 4 Homework #2 Name ________________________

Short Answer

1. If a competitive inhibitor (NOT an allosteric inhibitor) is added to a solution containing an enzyme that is regulated allosterically, the ratio of enzyme molecules in the active form to those in the inactive form increases. Explain why this might happen.

2. If water labeled with 18O is added to a suspension of phosynthesizing chloroplasts, which of the following compounds would first become labeled with 18O: ATP, NADPH, O2, or G3P? Which compound would first become labeled if the water were labeled with 3H? What if CO2 labeled with 14C were added?

3. You eat a burger containing polysaccharides, proteins, and lipids. Considering biochemical pathways, explain how the amino acids in the proteins and the glucose in the polysaccharides can end up as fats.

4. Compare the role of cohesins in mitosis, meiosis I and meiosis II.

5. If the dominant allele A is necessary for hearing in humans and another allele, B (located on a different chromosome), results in deafness no matter what other genes are present, what percentage of the offspring of the crossing of aaBb x Aabb will be deaf?

6. In cats, black coat (B) is codominant with orange (O). The coat color gene is sex-linked and only found on the X chromosome. Calico cats, which have coats with black and orange patches, are heterozygous for the coat color alleles.

a) Why are nearly all calico cats females?

b) A calico female has the following litter: 1 orange male, 2 black males, 2 orange females and 3 calico females. Assuming only one father, identify his genotype and phenotype.

7. The disease Leber’s optic neuropathy is caused by a mutation in a gene carried on mitochondrial DNA. What would be the phenotype of a child of a man with this disease and a woman who did not have the disease? What if the woman had the disease and the man did not?

Multiple Choice

1. Coenzymes differ from enzymes in that coenzymes are:

a. only active outside the cell b. smaller molecules, such as vitamins

c. specific for one reaction d. always carriers of high-energy phosphate

2. In a chemical reaction,

a. the rate depends on the G value b. the rate depends on the EA

c. the entropy change depends on EA d. the EA depends on the G value

3. Which statement about enzyme inhibitors is NOT true?

a. a competitive inhibitor binds the active site of the enzyme

b. an allosteric inhibitor binds a site on the active form of the enzyme

c. a noncompetitive inhibitor binds a site other than the active site

d. allosteric inhibitors are typically irreversible

4. In noncyclic photosynthetic electron transport, water is used to:

a. excite chlorophyll b. hydrolyze ATP

c. oxidize NADPH d. reduce chlorophyll

5. Which statement about chlorophylls is NOT true?

a. they absorbs light near both ends of the visible spectrum

b. they can accept energy from other pigments, such as carotenoids

c. excited chlorophyll can either reduce another substance or release light energy

d. excited chlorophyll cannot be an oxidizing agent

6. Photosynthesis in green plants occurs only during the day. Respiration occurs:

a. only at night b. only during the day

c. all the time d. in the chloroplast after photosynthesis

7. The role of oxygen gas in our cells is to:

a. catalyze reactions in glycolysis b. produce CO2

c. form ATP d. accept electrons from the ETC

8. Oxidation and reduction:

a. refer to the gain or loss of proteins b. are defined as the loss of electrons

c. are both endergonic reactions d. always occur together

9. Which statement about pyruvate is NOT true?

a. it is the end product of glycolysis b. it is oxidized during fermentation

c. it is a precursor of acetyl CoA d. it contains 3 carbon atoms

10. Fermentation:

a. takes place in the mitochondrion b. takes place in all animal cells

c. does not require O2 d. prevents glycolysis

11. Which statement about eukaryotic chromosomes is NOT true?

a. they sometimes consist of 2 chromatids b. they sometimes consist of 1 chromatid

c. they normally have a single centromere d. they consist only of protein

12. Which statement about cytokinesis is true?

a. in animals, a cell plate forms b. in plants, a cleavage furrow forms

c. it follows mitosis d. it involves the division of the nucleus

13. In meiosis:

a. homologous chromosomes separate from each other during anaphase I

b. DNA replicates between meiosis I and meiosis II

c. the chromatids that make up a chromosome in meiosis II are identical

d. meiosis II reduces the chromosome number from diploid to haploid

14. An animal has a diploid number of 12 (2n=12). An egg cell from this animal has 5 chromosomes. The most likely explanation for this is:

a. normal meiosis b. nondisjunction in meiosis I

c. normal mitosis c. nondisjunction in mitosis

15. The number of daughter chromosomes in a human cell (2n=46) in anaphase II is:

a. 2 b. 23

c. 46 d. 69

16. The phenotype of an individual:

a. depends at least in part on the genotype b. is either homozygous or heterozygous

c. determines the genotype d. is either monohybrid or dihybrid

17. Linked genes:

a. must be immediately adjacent to one another on a chromosome

b. have alleles that assort independently of each other

c. never show crossing over

d. are on the same chromosome

18. In epistasis:

a. one gene alters the effect of another b. a portion of the chromosome is deleted

c. a portion of the chromosome is inverted d. the behavior of 2 genes is independent

19. In humans, spotted teeth are caused by a dominant sex-linked gene. A man with spotted teeth whose father had normal teeth marries a woman with normal teeth. Therefore:

a. all of their daughters will have normal teeth

b. all of their daughters will have spotted teeth

c. all of their children will have spotted teeth

d. half of their sons will have spotted teeth