BME

Clemson University Biology Merit Exam

20 April 2007

Please choose the best answer for each of the following questions. Questions marked with an "*" are worth 4 points each; questions marked with a "#" are worth 2 points each; the unmarked questions are worth 1 point each.

CAUTION: Incomplete erasures and smudges can be read as marks. To avoid having a choice read incorrectly, make your marks lightly at first. After you have made all your changes, blacken in your marks just before you turn in your answer sheet.

The theme of this exam is rice, the world's largest crop, and the major source of food for over half the earth's people.

1. Of course, rice is a green plant. Which of the following cellular organelles would not be found in a plant cell?

a) a central vacuole b) mitochondria

c) chloroplasts d) All of these might be found in a plant cell.

2. Rice uses photosynthesis to grow, so we would say that it is

a) autotrophic. b) heterotrophic.

3. The process of photosynthesis uses ... to directly synthesize

a) H2O, NH3 and O2 ... proteins. b) CO2 and H2O ... sugar.

c) CO2 and O2 ... pyruvic acid. d) CO2 and O2 ... ATP, NADPH, and sugar.

4. Rice is a type of grass. Cultivated rice belongs to the species Oryza sativa (in Asia) or Oryza glaberrima (in West Africa). We know that O. sativa and O. glaberrima belong to the same

a) genus. b) family. c) order. d) All of these.

5.# Rice should not be confused with "wild rice" (Zazania). From the names Oryza and Zazania alone, we know that the two Oryza species and Zazania belong to

a) the same order but different families. b) the same families but different orders.

c) different genera. d) None of these conclusions are certain.

Some sources say that there are over 120,000 varieties of cultivated rice!

6.# Because rice is a grass, we also know that it is a ... and a(n)

a) monocot ... angiosperm. b) dicot ... angiosperm.

c) monocot ... gymnosperm. d) dicot ... gymnosperm.

7.* A diagram of a rice flower is shown below. While much of the terminology is highly technical and specific to grass flowers, does this diagram show both male and female reproductive organs?

a) Yes, it shows both. b) It shows female organs but not male ones.

c) It shows male organs but not female ones. d) No, it shows no reproductive organs.

8.# Rice flowers, like all grass flowers, are small and inconspicuous. This gives evidence that they

a) use swimming sperm. b) disperse spores rather than seeds.

c) have naked ovules. d) are wind-pollinated.

9.* Some sources say that domestication of rice probably occurred in China about 7,500 BC. At that time, living hominids on earth (not necessarily just in China) included

a) Homo neandertalensis. b) Homo sapiens.

c) Homo habilis. d) All of these.

10.# Rice is seeded into very crowded plots. Then, at about 30 days of age, the more successful seedlings are transplanted into level, diked fields (paddies) at a much lower density of about 30 plants per square foot. 30 plants per square foot is about ... plants per square meter.

a) 150 b) 180 c) 300 d) 900

11.# The paddies are flooded to a depth of about 12 inches. This flooding keeps weeds from growing, and in time the rice plants can be 2 m tall. A bad effect of these methods is that bacteria in the anaerobic soil produce methane. About 10-14% of the worldwide emissions of methane come from rice paddies. Methane is regarded as a pollutant mainly because it

a) is a greenhouse gas. b) destroys ozone in the upper atmosphere.

c) is very toxic to humans. d) contributes to acid rain.

Terraced rice paddies at Banaue in the Philippines. These paddies have been used for over 1,200 years!

12. Another environmental problem connected with rice in drier areas is salinization of land. Continuously wet soil wicks deep salts upward. Eventually, the salts accumulate on the soil surface when the water evaporates. Plants can't grow in the salty soil because the plant roots are ... to the soil and lose ... to the soil.

a) hypertonic ... minerals b) hypertonic ... water

c) hypotonic ... minerals d) hypotonic ... water

13.* In 2002, the rice genome was sequenced. It was found that the haploid rice genome has about 50,000 genes. This is about ... times as many genes as the haploid human genome has.

a) 0.02 b) 0.25 c) 0.5 d) 2.0

14.# Agricultural varieties of rice are diploid, and have 12 pairs of chromosomes. Say that chromosome 1 of a rice plant is large and chromosome 2 is smaller. Now imagine a rice cell in which only these two chromosomes are shown, and say that paternal chromosomes are dark and maternal ones are cross-hatched. Does the nucleus below show any valid phase of mitosis or meiosis?

a) Yes--mitotic telophase. b) Yes--meiotic telophase I.

c) Yes--mitotic prophase. d) No, this "phase" would not occur.

15.* Let us arrange all copies of dyad rice chromosomes 1 and 2 as follows with their centromeres uppermost:

Consider the top locus on each chromosome, indicated by the numbers 1-8. Assume crossing over does not occcur. Which of the statements below is true?

a) Locations 1, 2, 3, 4, 5, 6, 7, and 8 all govern the same traits.

b) 1, 2, 3, and 4 might have the same DNA, but 1 and 2 might have slightly different DNA from 3 and 4.

c) 5 and 7 must have the same DNA, and 6 and 8 must have the same DNA.

d) All of these.

16.* If crossing over did occur, we would expect it between locations ... above, but not between locations

a) 1 and 2 ... 2 and 3. b) 3 and 4 ... 4 and 5.

c) 3 and 5 ... 5 and 6. d) 6 and 7 ... 6 and 3.

17.* Rice is mostly self-fertilizing. Only 3-4% of fertilizations result from pollen from other rice plants. If a rice plant fertilizes its own flowers, what does this mean for the diversty of offspring that it will produce?

a) The offspring will all be genetically identical. This does not depend on the plant's genotype.

b) The offspring could all be genetically identical, but only if the plant is homozygrous at all its loci.

c) The offspring could all be genetically identical, but only if the plant is heterozygous at all its loci.

d) Due to random assortment of maternal and paternal chromosomes, the offspring will be genetically different. This does not depend on the plant's genotype.

18.* The rice plant sprouts extra stems called tillers. Tiller production is controlled at the T locus. TT plants have the most tillers, Tt plants have an intermediate amount, and tt plants have the fewest tillers. These tillers are only useful to the farmer if they have flowers on them. If they don't, they drain away resources without producing rice. Flowers are controlled at the F locus (on a different chromosome from the T locus), and tillers on Ff plants produce the most flowers. Either FF or ff tillers produce the same small number of flowers per tiller. If a TtFf plant fertilizes itself, the fraction of the offspring that will have the high-production TTFf genotype is

a) 1/2. b) 1/4 c) 1/8 d) 1/16

19.# The most common offspring genotype from the cross above will be

a) TtFf b) TTFF c) TTff d) TTFf

20.* While the T and F loci are on different chromosomes, say a rice variety is discovered in which T and F are on the same chromosome. Assume a TtFf parental plant has T and F on its maternal chromosome and t and f on its paternal chromosome. Assume that crossing over does not occur. If this plant fertilizes itself, it will be able to produce ... different offspring genotypes, and ... of these will be the high-production TTFf genotype.

a) 1 ... none b) 2 ... 1/4 c) 3 ... 1/8 d) 3 ... none

21.* The DNA of nine rice plants are treated with a restriction enzyme and electrophoresed. We suspect that these are three FF plants, three Ff plants, and three ff plants, but we can't be sure because the low-flower genotypes (FF and ff) look alike. We use a Southern blot to look at only the F locus. The results are shown below.

Our conclusions from this are that, probably

a) the F and f alleles are about the same size, and no plants are misclassified into the wrong genotype.

b) the f allele is smaller than the F allele, and plant 1 is really an ff plant.

c) the F allele is smaller than the f allele, and plants 2 and 3 are really Ff plants.

d) The F and f alleles are about the same size, and we were really wrong on our genotype classification. Plant 1 is is the only ff plant. Plants 2, 3, 4, 5, and 6 are FF, and plants 7, 8, and 9 are Ff.

22. Part of the F allele is the sequence TGTGCCGTG. Consider that last G, and the complete unit of which it is a part. In the structure of DNA, the G represents

a) a pyrimidine base. b) a phosphodiester bond.

c) a deoxy sugar with a base attached. d) a nucleotide.

23. Ff has more flowers than FF or ff because the F allele produces one part of a protein flower-producing hormone and the f allele produces the other part. Then both these parts come together to form the active protein hormone. The way two separate polypeptide chains fit together to form a functional protein is called that protein's

a) superdomain. b) motif.

c) concatenary domain. d) quaternary structure.

24.* These results are verified by an assay of tiller flower production in which both the F polypeptide and the f polypeptide are present together in varying concentrations. Which table below shows the expected results if effectiveness of the hormone is dependent on both the f and F polypeptides? The bolded number along the side are the concentration of each polypeptide. The numbers in the body of the table are the flowers per tiller.

25.# The rice hormone made by the F and f alleles has an effect only on the tiller cells that can develop flowers. This is probably because only these cells

a) have receptors for the hormone. b) can make the hormone.

c) can destroy the hormone. d) have the genes to make flowers.

26.# These hormone subunits are made of amino acids. An amino acid has an "alpha carbon" atom that always has four groups on it. Which of the following is not one of those groups bound directly to the alpha carbon?

a) a hydrogen atom. b) a carboxyl group. c) an hydroxyl group. d) an amino group.

27.* Carbon atoms usually have four bonds while oxygen atoms usually have two bonds because carbon ... while oxygen ... . Choose the reason most directly responsible.

a) has an s and a p subshell in its valence shell ... has a valence shell that only has an s subshell.

b) is not very electronegative ... is the second most electronegative element.

c) has an equal number of protons and neutrons ... has more neutrons than protons.

d) has four valence electrons ... has six valence electrons.

28.* The amino acids in this plant hormone are connnected by peptide bonds, as shown by answer

29. Transfer RNAs were used during the synthesis of the F and f polypeptides. These transfer RNAs got the amino acids in their correct spots in the polypeptide by

a) folding the mRNA until it matched the shape of the tRNA.

b) pairing their anticodons with codons in mRNA.

c) using ribozymes to synthesize a section of mRNA complementary to the tRNA.

d) using reverse transcriptase to make cDNA complementary to the mRNA.

30. The cellular organelle on which this protein synthesis occurred was the

a) mitochondrion. b) centriole. c) ribosome. d) nucleosome.

31.# The rice grain is mainly a seed that results from double fertilization. The ... results from fertilization by one sperm, and the ... results from fertilization by the other sperm.

a) pedicel ... ovule b) gametophyte ... sporophyte

c) stamen ... pistil d) endosperm ... embryo.

32.# Raw rice grains are about 79% starch. Once the seed is milled to remove its outer coatings, "white rice" is left. White rice at this stage of processing is almost pure starch. A human attempting to live on pure starch would soon need other foods to supply

a) amino acids. b) calories. c) glucose. d) All of these.

33.# When the digestion of the starch was complete, the monomers would travel to the individual's liver and would be stored there as

a) starch. b) amylose. c) glycogen. d) amylopectin.

34.# If our rice eater ate too much rice, he might need his ... to secrete some ... in order to keep his

a) adrenal glands ... glucocorticoids ... blood sugar from rising.

b) heart ... ANP ... blood pressure from falling.

c) liver ... bile ... blood sugar from falling.

d) pancreas ... insulin ... blood sugar from rising.

35.* Nutrient molecules coming from the rice-eater's liver would enter his heart at the ... . The blood in that chamber would have a relatively ... concentration of oxygen and a relatively ... concentration of CO2.

a) left atrium ... low ... low b) right atrium ... low ... high

c) left atrium ... high ... high d) right atrium ... high ... low

36.# The rice farmer will need all these nutrients if he finds that his rice is infected with a disease or is being eaten by pest insects. An imporant rice disease is bacterial blight, caused by the bacterium Xanthomonas oryzae. Which of the following would not be found in or on a bacterial cell?

a) a cilium b) a cell wall c) a ribosome d) a plasma membrane

37.* One of the most common rice pests is the stem borer, a moth larva that eats the inside the rice stem.

Stem borer larva in rice stem.

This insect is a member of the phylum ... and the order

a) Arthropoda ... Hymenoptera. b) Annelida ... Hirudinea.

c) Arthropoda ... Lepidoptera. d) Arthropoda ... Coleoptera.

38.# A farmer tries to control the stem borers by using an insecticide. No insecticide has ever been used in his field before. This will probably result in ... selection on the stem borers in the field.

a) stabilizing b) directional c) disruptive d) no consistent

39.* As the farmer is spraying the insecticide, he worries that the stem borers will become resistant to it. He knows that there is a stem borer allele for resistance to this insecticide. Which of the following situations would make the appearance of resistant stem borers more certain?

a) None of the stem borers in this area have the resistance allele.

b) Stem borers that have the resistance allele have different pheromones, and have a hard time attracting mates.

c) The resistance allele makes the stem borer adults slower and easier prey for birds.

d) Neighboring farms have used this insecticide for years, and the stem borer moths can easily fly long distances.

40. Ecologically, rice is a ... and the stem borer is a

a) primary producer ... primary consumer. b) primary consumer ... decomposer.

c) secondary producer ... secondary consumer. d) primary producer ... decomposer.