Biology Final Exam Review: Exam 3 – Flashcards

In eukaryotic cells, condensed chromosomes are composed of _____. A) DNA and histone proteins B) DNA and RNA C) DNA only D) DNA and phospholipids

What is the main purpose of light-dependent reactions of photosynthesis? A) to generate oxygen by "splitting" H2O B) to use ATP to make glucose C) to produce NADPH for use in respiration D) to produce NADPH and ATP

The first gap in the cell cycle (G1) corresponds to _____. A) the phase in which DNA is being replicated B) the beginning of mitosis C) the phase between DNA replication and the M phase D) normal growth and cell function

Which of the following are directly associated with photosystem I? A) receiving electrons from the thylakoid membrane electron transport chain B) extraction of hydrogen electrons from the splitting of water C) harvesting of light energy by ATP D) generation of molecular oxygen E) passing electrons to the cytochrome complex

The product of the p53 gene _____. A) causes cells to reduce expression of genes involved in DNA repair B) allows cells to pass on mutations due to DNA damage C) slows down the rate of DNA replication by interfering with the binding of DNA polymerase D) inhibits the cell cycle

What wavelength of light in the figure is most effective in driving photosynthesis? A) 625 mm B) 575 mm C) 730 mm D) 475 mm E) 420 mm Diagram on #6, exam 3

Diagram on #6, exam 3 Use the graph in the question above and the following information to answer the questions below. A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. Since the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed. What wavelengths of light should be used to maximize plant growth with a minimum of energy expenditure? A) a mixture of blue-violet and red light B) full-spectrum white light C) UV light D) green light E) yellow light

BRCA1 and BRCA2 are considered to be tumor-suppressor genes because A) the normal genes make estrogen receptors B) they prevent infection by tumor viruses that cause cancer C) their normal products participate in DNA repair D) they block penetration of breast cells by chemical carcinogens

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA? A) G2 B) G0 C) G1 D) M E) S

Quaking aspen can send out underground stems for asexual reproduction. Sexual reproduction is not as common, but when it does happen, the haploid gametes have 19 chromosomes. How many chromosomes are in the somatic cells of the underground stems? A) 38 B) 9 C) 19 D) 10

Which of these statements is correct? A) Single, haploid (2n) sets of chromosomes in ovum and sperm unite during fertilization, forming a diploid (4n), single-celled zygote. B) In humans, each of the twenty-three maternal autosomes has a homologous paternal chromosome. C) At sexual maturity, ovaries and testes produce haploid gametes by meiosis. D) In humans, the twenty-second pair, the sex chromosomes, determines whether the person is female (XY) or male (XX).

As electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy? A) It is used to establish and maintain a proton gradient. B) It is lost as heat. C) It excites electrons of the reaction center of photosystem I. D) It is used to phosphorylate NAD+ to NADPH, the molecule that accepts electrons from photosystem I.

The normal function of a tumor suppressor gene is to _____. A) promote progression of the cell cycle B) suppress the growth of tumors already present in all multicellular eukaryotes C) prevent meiosis D) prevent progression of the cell cycle unless conditions are right for moving forward

Energy from sunlight can excite electrons, kicking them out of their orbitals and creating free radicals. Free radicals are highly reactive atoms or molecules that have unpaired electrons and degrade and destroy other compounds in their vicinity. Carotenoids, one of the pigments present in most chloroplasts, can stabilize these free radicals. This suggests that _____.

Sexual reproduction _____. A) yields more numerous offspring more rapidly than is possible with asexual reproduction B) allows animals to conserve resources and reproduce only during optimal conditions C) guarantees that both parents will provide care for each offspring D) can produce diverse phenotypes that may enhance survival of a population in a changing environment E) enables males and females to remain isolated from each other while rapidly colonizing habitats

How is plant cell cytokinesis different from animal cell cytokinesis? A) Plant cells deposit vesicles containing cell-wall building blocks on the metaphase plate; animal cells form a cleavage furrow. B) The structural proteins of plant cells separate the two cells; in animal cells, a cell membrane separates the two daughter cells. C) The contractile filaments found in plant cells are structures composed of carbohydrates; the cleavage furrow in animal cells is composed of contractile phospholipids. D) Plant cells divide after metaphase but before anaphase; animal cells divide after anaphase.

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation. Surprisingly, this stops mitosis. Specifically, Taxol must affect _____. A) formation of the centrioles B) anaphase C) the structure of the mitotic spindle D) the S phase of the cell cycle E) chromatid assembly

In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and _____. A) water supply to the leaves has been reduced B) the degraded chlorophyll changes into many other colors C) carotenoids and other pigments are still present in the leaves D) sugars are sent to most of the cells of the leaves

C4 plants can close their stomata in the daytime, thus reducing loss of water. They can do this without a decline in photosynthesis because they _____. A) fix CO2 into sugars in the mesophyll cells B) use photosystem I and photosystem II at night C) fix CO2 into oxaloacetate (a C4 molecule) in the mesophyll cells and then shuttle the oxaloacetate into the bundle-sheath cells where decarboxylation and subsequent CO2 fixation occurs D) fix CO2 into organic acids during the night

The bulldog ant has a diploid number of two chromosomes. Therefore, following meiosis, each daughter cell will have a single chromosome. Diversity in this species may be generated by mutations and _____. A) crossing over B) nothing else C) independent assortment D) crossing over and independent assortment

The cancer-causing forms of the Ras protein are involved in which of the following processes? A) DNA repair B) DNA replication C) cell-cell adhesion D) relaying a signal from a growth factor receptor E) cell division

The electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the photosystem II replacement electrons come? A) photosystem I B) water C) oxygen D) the electron carrier, plastocyanin

What is the primary function of the Calvin cycle? A) split water and release oxygen B) transport RuBP out of the chloroplast C) use ATP to release carbon dioxide D) synthesize simple sugars from carbon dioxide E) use NADPH to release carbon dioxide

n colorectal cancer, several genes must be mutated for a cell to develop into a cancer cell. Which of the following kinds of genes would you expect to be mutated? A) genes that are especially susceptible to mutation B) genes coding for enzymes that act in the colon C) genes of the bacteria, which are abundant in the colon D) genes involved in control of the cell cycle

Why are there several structurally different pigments in the reaction centers of photosystems? A) This arrangement enables the plant to absorb light energy of a variety of wavelengths. B) They enable the reaction center to excite electrons to a higher energy level. C) Excited electrons must pass through several pigments before they can be transferred to electron acceptors of the electron transport chain. D) They enable the plant to absorb more photons from light energy, all of which are at the same wavelength.