5.1
What is the primary role of synapsis and crossing over during meiosis?
A. To create genetic diversity
B. To expand the meiosis process
C. To destroy DNA
D. To unswap genetic material
What is the significance of independent assortment of chromosomes during meiosis?
A. It increases genetic variation by allowing different combinations of alleles.
B. It ensures DNA repair.
C. It duplicates genetic material.
D. It reduces chromosome number by half.
A. It increases genetic variation by allowing different combinations of alleles.
Mendel's law of independent assortment is a result of:
A. Linked genes
B. Independent assortment only occurring during meiosis
C. The separation of sister chromatids in meiosis II
D. The random way homologous chromosomes line up in metaphase I of meiosis.
D. The random way homologous chromosomes line up in metaphase I of meiosis.
In a dihybrid cross between two heterozygous individuals (AaBb × AaBb), what is the expected phenotypic ratio?
A. 3:2:2:1
B. 9:3:3:1
C. 10:5:5:2
D. 9:3:4:1
B. 9:3:3:1
What term describes traits that are influenced by more than one gene?
A. Polygenic inheritance.
B. Monogenic (or Mendelian) trait
C. Pleiotropy
D. Multiple alleles
A. Polygenic inheritance.
Which of the following statements correctly describes a difference between mitosis and meiosis?
a) Mitosis produces 4 daughter cells, whereas meiosis produces 2 daugther cells.
b) Mitosis produces genetically different cells whereas meiosis produces genetically identical cells.
c) Mitosis produces somatoic cells, whereas meiosis produces gametes.
d) Mitosis produces haploid, whereas meiosis produces hiploid cells.
c) Mitosis produces somatic cells, whereas meiosis produces gametes.
Which event during sexual reproduction most directly increases genetic diversity in a population?
A. Mitosis
B. Crossing Over
C. DNA Replication
D. Binary Fission / Cloning
B. Crossing Over
Which of Mendel’s laws explains why alleles for different traits separate independently during gamete formation?
A. The Law of Segregation
B. The Law of Dominance
C. The Law of Independent Assortment
D. The Law of Unit Characters
C. The Law of Independent Assortment
A testcross is performed between an organism with genotype AaBb and an organism with genotype aabb. What proportion of offspring are expected to be aabb?
A. 50%
B. 100%
C. 25%
D. 75%
C. 25%
A plant species expresses red flowers only when grown in high‑light environments. In low light, the flowers appear white. Which concept best explains this phenomenon?
A. Codominance
B. Epistasis
C. Environmental influence on gene expression
D. Polygenic inheritance
C. Environmental influence on gene expression
For sexually reproducing diploid parent cells, what would explains the production of haploid cells that occurs in meiosis but not in mitosis?
A. Separation of chromatids occurs once, and there are two rounds of cell division in meiosis.
B. DNA replication occurs twice during the process, once before each division
C. The parent cell in meiosis is already haploid before division begins
D. Sister chromatids separate in the first meiotic division, while homologous chromosomes separate in the second
A. Separation of chromatids occurs once, and there are two rounds of cell division in meiosis.
Explanation: Separation of chromatids occurs once in meiosis, and there are two rounds of cell division, which ensures that haploid gamete cells are formed in sexually reproducing diploid organisms.
In a breeding pair of eukaryotic organisms, no crossing over occurs between chromatids of homologous chromosome pairs during either egg formation or sperm formation. Which of the following best explains the genetic makeup of the offspring produced when eggs are fertilized by sperm in this breeding pair?
A) All offspring will be genetically identical to the parent that has the greatest number of dominant traits.
B) Half of the offspring will be genetically identical to one parent and the other half will be genetically identical to the other parent.
C) All offspring will be genetically different from each other and from the parents.
D) The zygotes from fertilization will not develop into any offspring because of nondisjunction.
A) All offspring will be genetically different from each other and from the parents.
Explanation:Even without crossing over, independent assortment during meiosis ensures that different combinations of parental chromosomes will be present in gametes. When these gametes combine during fertilization, the offspring will have unique genetic combinations different from either parent.
In a cross between AaBb × aabb, what is the probability of producing an offspring with genotype aaBb?
A. 2/4
B. 1/32
C. 1/16
D. 1/4
D. 1/4
Reasoning:
A from Aa × aa → aa = 1/2
B from Bb × bb → Bb = 1/2
Multiply: 1/2×1/2=1/4
In a cross between Aabb × aaBb, what fraction of offspring are expected to have the genotype aa bb?
A. 1/2
B. 1/4
C. 1/16
D. 1/32
B. 1/4
Himalayan rabbits are a breed of rabbits with highly variable fur color. If genetically similar rabbits are raised in environments that have different temperature conditions, the rabbits can have different color patterns.
Which of the following statements best explains how the fur color can be different in Himalayan rabbits raised under different temperature conditions?
A) The genotype does not contribute to coat color in Himalayan rabbits.
B) The phenotype determines the genotype of coat color in Himalayan rabbits.
C) Different environments cause specific mutations in the genes controlling pigment production.
D) The environment determines how the genotype is expressed.
D) The environment determines how the genotype is expressed.
Explanation: . The environment influences gene activity, which leads to a change in the phenotype of fur color. Temperature is the most significant environmental factor in determining the coat color of these rabbits.
A cell begins meiosis with 12 chromosomes. How many chromosomes will each gamete contain after meiosis is complete?
A. 3
B. 6
C. 12
D. 24
B. 6
Reasoning: Meiosis halves the chromosome number.
A researcher observes that in a certain plant species, the alleles for flower color and leaf shape assort independently. Which meiotic event best explains this observation?
A. Separation of sister chromatids during anaphase II
B. Crossing over between homologous chromosomes
C. Random alignment of homologous chromosome pairs during metaphase I
D. Cytokinesis following telophase I
C. Random alignment of homologous chromosome pairs during metaphase I
In the cross AaBbCc x AaBBCc, what is the probability of producing an offspring with the AABBCc genotype?
A. 1/4
B. 1/2
C. 1/16
D. 1/32
D. 1/32
A plant with genotype AaBbCc is crossed with a plant with genotype aabbCc. Assuming independent assortment, what is the probability of producing an offspring with genotype Aabbcc?
A. 1/32
B. 1/16
C. 1/8
D. 1/4
B. 1/16
Reasoning
A from Aa × aa = 1/2
bb from Bb × bb = 1/2
cc from Cc × Cc = 1/4
Multiply: 1/2×1/2×1/4=1/16. Aabbcc requires A (1/2), bb (1/2), cc (1/4) → 1/16.
The tadpoles of Mexican spadefoot toads are known to exhibit phenotypic plasticity depending on food availability. Tadpole mouthparts can vary significantly, prompting researchers to categorize them as either omnivore-morph or carnivore-morph. Carnivore-morph tadpoles are larger and have mouthparts that are better suited for predation. Remarkably, carnivore-morph tadpoles can change into omnivore-morph tadpoles when the food supply changes.
Which of the following best describes an advantage of the phenotypic plasticity displayed by the tadpoles?
A) It allows the tadpoles to change their genome in response to environmental pressures.
B) It enables the tadpoles to develop into a distinct species of toads.
C) It gives the tadpoles increased versatility with respect to diet.
D) It allows the tadpoles to delay metamorphosis until there is maximal food available for the adults.
C) It gives the tadpoles increased versatility with respect to diet.
Explanation: Phenotypic plasticity during development is an adaptation in Mexican spadefoot toads that allows the tadpoles to best exploit the available resources in different environments.
Which of the following processes explains how genetic variation results from meiosis and contributes to evolution?
A. Mutations, crossing over, and random fertilization
B. Mitosis, DNA replication, and cell division
C. Genetic drift, natural selection, and gene flow
D. Photosynthesis, cellular respiration, and transpiration
A. Mutations, crossing over, and random fertilization
What occurs during Anaphase I of meiosis?
A. Sister chromatids separate
B. Homologous chromosomes separate
C. Chromosomes condense
D. Nuclear envelope reforms
B. Homologous chromosomes separate
Researchers performed a dihybrid cross with coffee bean plants to investigate whether the inheritance of two traits (height and stem circumference) follows Mendel’s law of independent assortment. The data for the F2 generation are presented in Table 1.
Table 1. Data for the generation
Phenotype Observed Expected
Dwarf with small 191 172
Dwarf with large 26 57
Tall with small 39 57
Tall with large 49 19
TOTAL 305 305
What would be the closest to the calculated chi-square (x2 ) value for the data presented in Table 1?
A. 8.35
B. 72.01
C. 98.00
D. 2,546.00
FROM COLLEGE BOARD PROGRESS CHECK.
B. 72.01
Which blood type is an example of codominance?
A. AB
B. O
C. A
D. B
A. AB
Which of the following is NOT an example of environmental effects on phenotype?
A. A plant growing taller due to increased sunlight.
B. A human developing stronger muscles due to exercise.
C. A person's skin color changing after being in the sun.
D. A child inheriting blue eyes from their parents.
D. A child inheriting blue eyes from their parents.