Question 1

Which of the following statements is true of homologous chromosomes?
A) They come in pairs.
B) They move together into the gametes during meiosis.
C) They are found only in mammals.
D) They have three codons.

Accepted Answer

Homologous chromosomes come in pairs, with one chromosome from each parent. They carry the same genes (although not necessarily the same alleles) at corresponding locations, and they undergo crossing over during meiosis. The other statements are not true: homologous chromosomes do not move together during meiosis (rather, they separate), and they are found in a wide variety of organisms, not just mammals. Finally, chromosomes do not have codons, which are sequences of nucleotides in mRNA that code for amino acids.

Question 2

Which of the following occurs during mitosis?
A) A haploid cell divides into two diploid cells.
B) A diploid cell divides into two haploid cells.
C) A haploid cell divides into two haploid cells.
D) A diploid cell divides into two diploid cells.

Accepted Answer

During mitosis, a diploid cell divides into two identical diploid cells. This process is important for growth and repair of tissues in multicellular organisms, as well as for asexual reproduction in some single-celled organisms. Option A is incorrect because mitosis does not involve a change in ploidy, and option B is incorrect because diploid cells cannot divide into haploid cells during mitosis. Option C is incorrect because mitosis typically results in two identical daughter cells, but these cells are still diploid if the parent cell was diploid.

Question 3

What does Mendel's second principle (of independent assortment) state?
A) Eggs and sperm are formed independently of one another.
B) Transmission includes both blending and particulate inheritance.
C) The inheritance of one trait does not affect the inheritance of another trait.
D) Particles inherited from the mother are more likely to be transmitted to female offspring, and particles inherited from the father are more likely to be transmitted to male offspring.

Accepted Answer

Mendel's second principle, also known as the law of independent assortment, states that the inheritance of one trait is not affected by the inheritance of another trait. This means that the segregation of alleles for one gene is independent of the segregation of alleles for another gene. In other words, the way in which one trait is inherited does not influence how another trait is inherited.

Question 4

When Mendel crossed true-breeding pea plants bearing yellow seeds, the offspring bore
A) all yellow seeds.
B) one-half yellow and one-half green seeds.
C) three yellow seeds and one green seed.
D) all green seeds.

Accepted Answer

True-breeding pea plants will always produce offspring with the same phenotype as the parent. In this case, the parent plants had yellow seeds, which is a dominant trait. Therefore, all of the offspring will also have yellow seeds because they inherited at least one dominant allele from each parent.

Question 5

Mendel's crossbreeding of offspring of true-bred green and yellow peas led to ________ in the second generation.
A) only green individuals surviving the first days of life
B) a 3:1 ratio of yellow to green offspring
C) yellowish-green individuals
D) half the offspring being green and the other half yellow

Accepted Answer

Mendel's crossbreeding of true-bred green and yellow peas resulted in all of the offspring in the first generation being yellow. However, when these yellow offspring were allowed to self-fertilize or were crossbred with another true-bred yellow individual, the second generation showed a clear 3:1 ratio of yellow to green offspring. This ratio demonstrated that the green trait had been present in the first generation, but had been masked by the dominant yellow trait.

Question 6

If you have two parents with the genotype Aa, what is the chance that they will have an offspring with the genotype AA?
A) one-eighth
B) one-half
C) one-fourth
D) one-sixteenth

Accepted Answer

Each parent has one dominant A allele and one recessive a allele. When they reproduce, each parent can contribute either the dominant A allele or the recessive a allele to their offspring. The possible combinations for their offspring are AA, Aa, Aa, and aa. Since AA requires both parents to contribute the dominant A allele, the chance of having an AA offspring is 1 out of 4 or 25%, which is equivalent to one-fourth. Therefore the correct answer is C) one-fourth.

Question 7

The DNA sequence ATATATATATATATATATATATATAT is
A) a common regulatory sequence first discovered in fruit flies.
B) the most common sequence making up introns.
C) the most common sequence making up exons.
D) a simple repeat pattern usually found in specific sites in a given eukaryote.

Accepted Answer

The DNA sequence ATATATATATATATATATATATATAT is a simple repeat pattern usually found in specific sites in a given eukaryote. These sites are called satellite DNA, and they are often found in the centromere region of chromosomes.

Question 8

Which of the following statements describes gametes?
A) They contain both homologous chromosomes.
B) They are responsible for normal body growth of organisms.
C) They can be eggs or sperm.
D) They are diploid.

Accepted Answer

Gametes are reproductive cells that can be either eggs or sperm. They are produced by meiosis and contain only half the number of chromosomes (haploid) as the parent cell.

Question 9

One of Mendel's pea plants with only green seeds is
A) homozygous recessive.
B) always tall.
C) an example of blending inheritance.
D) heterozygous.

Accepted Answer

Only pea plants with two recessive alleles for seed color (gg) would produce all green seeds, making them homozygous recessive for the gene controlling seed color.

Question 10

Where are chromosomes contained?
A) in the gametes of prokaryotes
B) in the nuclei of eukaryotes
C) in the ribosomes
D) in the mitochondria

Accepted Answer

Chromosomes, which contain genetic material in the form of DNA, are found within the nuclei of eukaryotic cells. They are not present in the gametes of prokaryotes, nor in the ribosomes or mitochondria.

Question 11

Which of the following is the result of mitosis?
A) half the number of chromosomes in the daughter cells
B) either sperm or an egg
C) a daughter cell that has the exact copy of the chromosomes of its parent
D) an egg only

Accepted Answer

Mitosis results in the formation of two daughter cells, each with an exact copy of the parent cell's chromosomes. This ensures that each daughter cell has the same genetic material as the parent cell. Option A is incorrect because mitosis does not reduce the number of chromosomes; it maintains the same number. Option B is incorrect because mitosis involves the division of somatic cells, not the creation of gametes (sperm or eggs). Option D is incorrect because mitosis does not produce eggs exclusively; it can produce any type of somatic cell.

Question 12

Which of the following statements is true of chromosomes?
A) They are composed of ribonucleic acid.
B) They are replicated during cell division.
C) They are attached to organelles.
D) They are made of proteins.

Accepted Answer

Chromosomes are replicated during cell division through a process called DNA replication. They are not composed of RNA, attached to organelles, or made of proteins alone. They consist of DNA wrapped around proteins, which together form a structure known as chromatin.

Question 13

Why is it important to understand the overall relationship between genes, proteins, and chemical reactions in cells?
A) Many changes in the morphology or behavior of organisms can be linked to variations in the proteins and genes that build them.
B) Genetic effects on the biology of organisms account for as much as 10% of the variation we see from species to species.
C) Although most evolutionary change is extracellular, it is sometimes influenced by genetic systems.
D) Only by controlling these relationships can we treat most disease symptoms.

Accepted Answer

Understanding the relationship between genes, proteins, and chemical reactions in cells is important because many changes in the morphology or behavior of organisms can be linked to variations in the proteins and genes that build them. This knowledge is essential for developing new treatments for diseases, understanding evolutionary processes, and potentially manipulating genetic systems for human benefit.

Question 14

Which of the following is true of diploid organisms?
A) Chromosomes occur in homologous pairs.
B) Chromosomes occur in homologous triplets.
C) Meiosis produces diploid gametes.
D) Mitosis produces haploid cells.

Accepted Answer

Diploid organisms have two sets of chromosomes, with each chromosome in the set having a matching copy, or homologous pair. Meiosis produces haploid gametes, not diploid gametes. Mitosis produces cells that have the same number of chromosomes as the parent cell, so it does not result in the production of haploid cells.

Question 15

Which of the following statements is true of gametes?
A) They are not involved in the transmission of genes.
B) They are the sex cells, or eggs and sperm.
C) They do not differ between male and female animals.
D) They were discovered by Darwin.

Accepted Answer

Gametes are the sex cells, or eggs and sperm, that are involved in sexual reproduction and transmit genetic information from one generation to the next. They differ between male and female animals, and were not discovered by Darwin, as their role in reproduction was not fully understood until the early 20th century.

Question 16

To what does the genotype of an individual refer?
A) the alleles it carries
B) its visible characteristics
C) the number of chromosomes in its sex cells
D) the number of chromosomes in its body cells

Accepted Answer

The genotype of an individual refers to the specific combination of alleles it carries, which determines its genetic information and potential traits.

Question 17

Mendel observes a pea plant with yellow seeds, where A and a are the alleles for color, but he knows nothing else about the plant. Which of the following must he infer is the possible genotype(s) of this plant?
A) AA only
B) AA or aa
C) Aa only
D) AA or Aa

Accepted Answer

Since the plant has yellow seeds, it must have at least one dominant allele (A). Therefore, the possible genotypes are either homozygous dominant (AA) or heterozygous (Aa).

Question 18

Reduction of chromosome number occurs during
A) recombination.
B) meiosis.
C) somatic cell formation.
D) gene linking.

Accepted Answer

Reduction of chromosome number occurs during meiosis, specifically during meiosis I, where homologous chromosomes separate and the resulting cells have half the chromosome number of the original cell. Recombination and gene linking may occur during meiosis but do not directly result in a reduction in chromosome number. Somatic cell formation does not involve meiosis and therefore does not result in a reduction of chromosome number.

Question 19

What does Mendel's first principle (of segregation) imply?
A) Characteristics from the parents blend together to produce intermediate offspring.
B) Characteristics from the parents do not blend together in offspring.
C) Only paternally derived characteristics segregate into gametes during meiosis.
D) Only maternally derived characteristics segregate into gametes during meiosis.

Accepted Answer

Mendel's first principle, also known as the principle of segregation, implies that characteristics from the parents do not blend together in offspring. Instead, they remain distinct and segregate into separate gametes during meiosis. This is the basis for the inheritance of discrete traits in genetics. Therefore, option B is correct. Options A, C, and D are incorrect as they do not accurately describe Mendel's first principle.

Question 20

Which of the following occurs during meiosis?
A) Haploid cells are produced from a single diploid cell.
B) Haploid cells are produced from two diploid cells.
C) Diploid cells are produced from a single diploid cell.
D) Diploid cells are produced from two haploid cells.

Accepted Answer

Meiosis is a type of cell division that results in the formation of haploid cells from a single diploid cell. Specifically, meiosis involves two rounds of cell division, known as meiosis I and meiosis II, which result in the formation of four haploid daughter cells from a single diploid parent cell. During meiosis I, homologous pairs of chromosomes separate, while during meiosis II, sister chromatids separate. The end result is four genetically diverse haploid cells, as opposed to two genetically identical diploid cells produced during mitosis.

Quiz 2: Genetics

Which of the following statements is true of homologous chromosomes?

Which of the following occurs during mitosis?

What does Mendel's second principle (of independent assortment) state?

When Mendel crossed true-breeding pea plants bearing yellow seeds, the offspring bore

Mendel's crossbreeding of offspring of true-bred green and yellow peas led to ________ in the second generation.

If you have two parents with the genotype Aa, what is the chance that they will have an offspring with the genotype AA?

The DNA sequence ATATATATATATATATATATATATAT is

Which of the following statements describes gametes?

One of Mendel's pea plants with only green seeds is

Where are chromosomes contained?

Which of the following is the result of mitosis?

Which of the following statements is true of chromosomes?

Why is it important to understand the overall relationship between genes, proteins, and chemical reactions in cells?

Which of the following is true of diploid organisms?

Which of the following statements is true of gametes?

To what does the genotype of an individual refer?

Mendel observes a pea plant with yellow seeds, where A and a are the alleles for color, but he knows nothing else about the plant. Which of the following must he infer is the possible genotype(s) of this plant?

Reduction of chromosome number occurs during

What does Mendel's first principle (of segregation) imply?

Which of the following occurs during meiosis?