Biology-Test #3

Assume that in cattle a spotted coat is dominant to a solid-colored coat, short horns are dominant to long horns, and the traits for coat color and horn length assort independently. In a cross between cattle that are heterozygous for both traits, what proportion of their offspring is expected to have long horns?

1/4

A typical monohybrid cross between two plants heterozygous for one character (Pp, purple flowers) yields which of the following genotypic ratios?

1PP; 2Pp; 1pp

Imagine that Gene X has 15 different alleles. What is the maximum number of different alleles of Gene X that can be present in an individual?

2

How many chromosomes are present in a human cell that is in the process of dividing before the sister chromatids have separated?

46 duplicated chromosomes

About __________ % of the products of photosynthesis are used to power cellular respiration and to make organic molecules that the plant cells need. What happens to the rest of the products?

50%; stored or made into cellulose

A woman who is a carrier of hemophilia marries a man affected with hemophilia. What percentage of their sons and daughters re expected to have hemophilia?

50%of sons & 50% of daughters

Imagine a group of eight couples who meet each week to line-dance. Each couple consists of two people. Using the language of genetics, you could say that the haploid number of dancers is __________. The diploid number of dancers is __________. The tetraploid number of dancers is __________.

8; 16; 32

How many molecules of ATP and NADPH are required to make one molecule of G3P in the Calvin cycle?

9 ATP; 6 NADPH

In Labrador retrievers, black coat is dominant to chocolate, normal vision is dominant to progressive retinal atrophy (PRA), and normal hip joint is dominant to hip dysplasia. The alleles for all of these traits assort independently. Two dogs that are heterozygous for alleles of all three genes are crossed. Using rules of probability (not a Punnett square), what is the chance that the first pup born to these dogs will be chocolate, have normal vision, and have normal hip joints?

9/64

What was the evidence from dihybrid cross experiments on flower color and pollen shape, obtained in the early 1900s, that supports the existence of linked genes?

A higher proportion of some phenotypes and a lower proportion of other phenotypes than was predicted by Mendelian laws

In genetics, two varieties of the same species of plant that reproduce by cross-fertilization create __________ plant. The offspring of these organisms are the __________ generation of the original plants.

A hybrid; F2

In a karyotype, how can you distinguish a trisomy from a chromosome duplication?

A trisomy is an extra chromosome; a duplication is an extra segment on one chromosome.

Photosystems I and II work together to produce __________.

ATP and NADPH

What causes sickling of red blood cells in people who have sickle cell disease?

Abnormal hemoglobin is produced in a person homozygous for the sickle-cell allele.

A 2015 study of women with ductal carcinoma in situ (DCIS) told oncologists that the overall risk of death from breast cancer was about 3.3% in women who had been diagnosed with the condition. What else did the study show?

About 20% of women with DCIS were at much a higher risk.

Which of the following outcomes of a mating between a red flower (RR) and a white flower (rr) illustrates incomplete dominance?

All members of the F1 generation have pink flowers.

In a laboratory experiment, cancer cells that had been rapidly dividing began to slow their rate of division. What could account for this?

An inhibitor of vascular endothelial growth factor (VEGF) was added to the growth medium

How is sex determined in ants and bees?

By the number of chromosomes

Which of the following statements about cancer cells and the cell cycle is INCORRECT?

Cancer cells are fixed at the S stage.

List the three most important greenhouse gases. What positive effect do these gases exert on Earth's atmosphere?

Carbon dioxide, methane, water vapor; insulation

Several methods are now available for diagnosing genetic disorders in fetuses. Which of the listed commonly available methods provides genetic information at the earliest point in pregnancy?

Chorionic villus sampling (CVS)

Imagine that long fins in zebrafish is a dominant trait. A breeder wants to set up a breeding program beginning with homozygous dominant long-finned fish. If she obtains several long- and short-finned fish, how can she tell which, if any, are homozygous for the trait that she wants?

Cross the long-finned fish with the short-finned fish; if the offspring are all long-finned, the long-finned parent is homozygous.

The most common lethal genetic disease in the United States is __________, a __________ disorder. Its characteristic symptom is __________.

Cystic Fibrosis; recessive; excess mucus production

The phrase cleavage furrow is associated with all of the following except __________.

Cytokinesis in a plant cell

Which of the following is a true statement for mitosis but NOT meiosis?

Daughter cells are used for tissue repair.

Which of the following are the most harmful types of alterations in chromosomal structure?

Deletion

You breed mice. Because you've studied genetics, you know that mouse body size could be the result of (1) one gene with alleles that show incomplete dominance or (2) multiple genes (a polygenic character). How could you distinguish between these two possibilities, starting with a large-bodied female and a small-bodied male?

Determine whether F2 mice "come in" three size classes (consistent with incomplete dominance of a "size" allele) or in a range of sizes (consistent with polygenic inheritance).

You applied two drugs, A and B, to two colonies of cancer cells in the laboratory. This type of cell normally takes about two days to double. When you examine your cultures two days later, you find that the number of cells treated with Drug B has indeed doubled, while the number of cells treated with Drug A has hardly changed. What might you conclude?

Drug A arrested cell growth in phase G1.

Without knowing what characteristics these letters represent, you can tell that an insect with the genotype EeGGcc will have the same phenotype as an insect with the genotype __________.

EEGgcc

If you expressed Mendel's law of independent assortment using modern terminology, you would say that __________.

Each pair of alleles segregates independently of other pairs during gamete foundation.

Brittany marries a man with a rare single-gene blood disorder that is heritable and recessive. They have two children, each of whom develops this disorder. Neither Brittany nor her two siblings have this disorder. What were the genotypes of Brittany's parents for this disorder?

Either or both of her parents are heterozygous for the trait.

Which of the following statements regarding the reduction of CO2 to sugar during photosynthesis is correct?

Electrons (with accompanying protons) from water are transferred to CO2 during photosynthesis

What is the immediate effect of light on chlorophyll in an experimental system?

Electrons are boosted to higher energy levels, and then emit light and heat when they fall to ground state.

The reduction of NADP+ to NADPH in the light reactions occurs with the assistance of __________.

Electrons from water and energy from sunlight

How does photosynthesis contribute to climate change? In what way is it a solution to climate change?

Fossil fuels produce CO2 when burned. Plants remove CO2 from the atmosphere in photosynthesis.

Cells that do not divide are in phase __________ of the cell cycle. Which cell types live in this phase?

G0; mature neurons and muscle cells

__________ waves are the shortest waves in the electromagnetic spectrum, while __________ waves are the longest. Which of these waves has the higher energy in its photons?

Gamma; radio; gamma

In constructing the genetic linkage map for a chromosome, scientists use which of the following known facts?

Genes with higher crossover frequencies are located farther from each other than genes with lower crossover frequencies.

Sex cells in humans contain the __________ number of chromosomes, which is __________.

Haploid; 23

A monohybrid cross is a cross between two individuals that are __________. A dihybrid cross is a cross between two individuals that are __________.

Heterozygous for one character; heterozygous for two characters

Several genetic tests are available to detect genetic disorders in prospective parents, newborns, and others. Despite the increasingly sophisticated methods of prenatal diagnosis that are available, there are ethical concerns with such technologies. Which of the following is NOT an ethical concern linked to prenatal or newborn screening?

How are prenatal diagnostic tests performed and how soon are results available?

Name the alleles that result in the ABO blood group phenotypes.

IA, IB, i

What characteristic of the Y chromosome makes it so useful for studying the evolution of the male human being?

It passes virtually intact from father to son.

Why are lethal dominant alleles much less common than lethal recessive alleles?

Lethal dominant alleles are harmful even when carried by heterozygotes, so there is strong selective pressure against these alleles.

You have two dogs: a brown Labrador retriever and its sister, who is black. In these dogs, the B allele (black) is dominant over the b allele (brown). A bb dog is brown. Which of the following parent genotypes could NOT have resulted in the litter to which both of your dogs belong?

Mother BB x Father Bb

What is the final electron acceptor in the light reactions of photosynthesis?

NADP

Two separate processes occur in the light reactions of photosynthesis. In one, __________ is generated as the result of an electric transport chain. In the other, the high concentration of __________ in the thylakoid space drives the synthesis of __________.

NADPH; H+; ATP

Imagine you're counseling a couple who have undergone screening for Tay-Sachs disease. The man is a carrier of the Tay-Sachs allele and the woman is not. What information should you give them regarding any children they might have?

No child will have Tay-Sachs disease, but there is a 50% chance that a child will be a carrier of the Tay-Sachs allele.

The light reactions of photosynthesis yield __________. The Calvin cycle produces __________.

O2, ATP, NADPH; sugar, ADP, NADP+

In an individual of genotype Aa, where are the A and a alleles physically located?

One allele is on a chromosome from the individual's female parent, and the other is in the same position (locus) on the homologous chromosome from the male parent.

In fruit flies, R is the dominant, red-eye allele and r is the recessive, white-eye allele. White eye color is a sex-linked recessive trait; there is no locus for eye color on the Y chromosome. Which of the following is the outcome of a mating between a dominant heterozygote female (XRXR) and a male that is XrY?

One-half of the females have red eyes and are carriers for white eyes.

Imagine that an ancient Greek man had huge muscles from lifting heavy stone tablets. His wife was small and frail. What would Hippocrates have predicted regarding their son?

Pangenes passed from father to son would ensure that the son had huge muscles.

What is the molecular basis for hypercholesterolemia in a person who is homozygous for the recessive allele h?

People who are hh have no cell-surface receptors for LDL cholesterol.

Which of the following statements is NOT true of Down syndrome?

People with Down syndrome have an approximately normal lifespan.

Imagine a particular character (such as flower color) that is determined by a single gene. If this gene is present in two forms, how can you tell which allele is dominant and which is recessive?

Perform a cross between two true-breeding individuals that differ for the trait and observe the traits expressed in the F1 individuals.

What is the most important function of carotenoid pigments in plants?

Protect cells from excess sunlight

Most alleles that cause human genetic disorders are __________.

Recessive

Which choice lists the time periods of the phases of the cell cycle correctly from longest phase to shortest phase?

S, G2, mitosis

Which of the following occurs in Meiosis II?

Sister chromatids are separated.

Nondisjunction during meiosis II results in which of the following?

Some gametes have an abnormal number of chromosomes.

Which of the following organelles can open or close? Thylakoids are found in the __________ of the chloroplast.

Stomata; stroma

Scientists used isotopes to identify the source of oxygen released during photosynthesis. What did they discover?

The O2 comes from water, not CO2

Why do nondisjunctions of the sex chromosomes usually have a less dramatic impact on a person's life than nondisjunctions of somatic chromosomes?

The Y chromosome is small, and females have only one functional copy of an X chromosome.

In a hedgehog, what is a correct statement regarding the relationship between the base sequences of DNA in two sister chromatids?

The base sequences are identical.

The chromosome theory of inheritance holds that __________.

The behavior of chromosomes during meiosis and fertilization determines inheritance patterns.

In Morgan's testcross of a gray-bodied, long-winged heterozygous female Drosophila melanogaster (fruit fly) with a homozygous recessive black-bodied, vestigial-winged male, the following offspring were obtained: 965 gray body, long wing; 944 black body, vestigial wing; 206 gray body, vestigial wing; 185 black body, long wing. What did these results show?

The genes for body color and wing length are linked; recombination of alleles has occurred.

Growth factors signal the control system of a cell's cell cycle. What is the first event in the signaling process?

The growth factor binds to a receptor on the cell's plasma membrane.

What would be the immediate effect on mitosis of destroying a cell's centrosomes?

The mitotic spindle would not form.

To what do the letters "A," "B," "AB," and "O" refer when describing ABO blood group phenotypes?

The presence of one of two carbohydrates (Aor B) on the surface of red blood cells

What is the meaning of random fertilization?

The probability that a given egg and a given sperm will fuse is random.

How have CAM plants adapted to survive in arid environments?

Their stomata open only at night.

If the gene for pea seed color that Mendel studied exhibited pleiotropy, how might a green seed be different from a yellow seed?

There would be other differences between the two seeds; for example, the green seeds could be larger, ripen earlier, or be more sensitive to frost.

What causes the sister chromatids to move toward opposite poles of the cell in anaphase?

They are pulled by spindle microtubules attached at the kinetochore.

Which blood group is considered the "universal donor"?

Type O

How are cells obtained for constructing a karyotype?

White blood cells are cultured and stained.

The dominant phenotype of a single-gene trait called Z results from the genotype __________. The recessive phenotype results from the genotype __________.

ZZ or Zz; zz

Which of the following is present in plants like corn and sugar cane?

a carbon-fixing enzyme with high affinity for CO2

What are homologous chromosomes?

a matched pair of chromosomes that may have different genes at the same loci

Women with Turner syndrome display which of the following sex chromosome abnormalities and characteristics?

a single X chromosome; short stature and infertility

A recessive allele h is associated with high cholesterol. hh homozygotes have extremely high levels of LDL ("bad") cholesterol, while HH heterozygotes have low (normal) levels of LDL cholesterol. The H allele is incompletely dominant to the h allele. What do you predict would be the LDL cholesterol levels in someone who is heterozygous (Hh) for this character?

between low and very high

Asexual and sexual reproduction differ in that sexual reproduction __________.

can produce genetic variation among the offspring

Plants remove __________ from the atmosphere and return __________ to the atmosphere. The other product(s) of photosynthesis is (are) __________.

carbon dioxide; oxygen; sugars

In genetics, a heritable feature that varies among individuals is called a __________. Each variant of such a feature is called a __________.

character; trait

In prokaryotes, binary fission includes which of the following?

copying the parental chromosome into daughter cells

Which event precedes cell division in both eukaryotes and prokaryotes?

duplication of DNA

At the conclusion of meiosis I, the daughter cells are __________.

haploid and the sister chromatids are joined

Meiosis results in __________ gametes in __________ organisms. When gametes combine, the resulting zygote is __________.

haploid; diploid; diploid

An organism with two non-identical alleles for the same gene is said to be __________ for that gene (and trait). What is true of these alleles?

heterozygous; One is dominant and the other is recessive.

At what point in the cell cycle is DNA synthesized in a eukaryotic cell that is NOT a nerve or a muscle cell?

in the S phase of interphase

What happens when poison ivy and other plants are exposed to elevated levels of CO2?

increased growth of poison ivy, more potent urushiol

Based on our current understanding of genetics, the role of the environment in a character __________.

is to work with genes in complex and often unknown ways in the expression of many characters

Which of the following are photoautotrophs?

kelp, a large sea alga

Chloroplasts are located in __________ cells. Each such cell contains __________ chloroplasts. Chlorophyll molecules are located on membranes of the __________.

mesophyll; 30-40; thylakoids

The blood group phenotypes of several siblings are Type A, 50%; Type AB, 25%; and Type B, 25%. What genotypes are the parents?

one parent, IA/IB; the other parent, IA/i

Crossing over occurs in stage __________ of meiosis. It involves the exchange of genetic information between two __________ chromatids of homologous chromosomes.

prophase I; nonsister

The chromosomes created by crossing over are called __________ chromosomes.

recombinant

At which step of the 4-step Calvin cycle is G3P produced?

reduction, step 2

Mendel ensured that his pea plants could not self-fertilize by __________. The first generation of offspring after the plants had been bred was the __________ generation.

removing the stamens from the flowers to be fertilized; F1

Two important discoveries were made at about the same time: the source of oxygen in photosynthesis, and the details of the Calvin cycle. When were these discoveries made?

the 1950s

In the light reactions, __________ and an __________ transform __________ energy into __________ energy of ATP and NADPH.

two photosystems; electron transport chain; light; chemical