Question 1

Which of the following best describes the difference between a gene and an allele?

Accepted Answer

A gene is a specific sequence of DNA that codes for a protein, while an allele is a variant form of that gene.

Question 2

During which phase of mitosis do sister chromatids separate and move toward opposite poles of the cell?

Accepted Answer

Anaphase

Question 3

A cell with a diploid number of 8 ($$2n = 8) $$undergoes meiosis. How many chromosomes will each gamete contain after meiosis is complete?

Accepted Answer

$$4$$

Question 4

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

They carry the same genes but may have different alleles.

Question 5

In Mendel’s dihybrid cross between plants with yellow round seeds ($$YYRR) $$and green wrinkled seeds ($$yyrr$$), what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$$9:3:3:1$$

Question 6

Which protein complex is primarily responsible for holding sister chromatids together until anaphase?

Accepted Answer

Cohesin

Question 7

A testcross is performed between a pea plant with an unknown genotype for seed color (yellow is dominant, green is recessive) and a homozygous recessive plant. If all offspring are yellow, what is the genotype of the unknown parent?

Accepted Answer

Homozygous dominant ($$YY)$$

Question 8

Which of the following best explains the principle of independent assortment at the chromosomal level?

Accepted Answer

During metaphase I of meiosis, homologous chromosome pairs align independently of each other.

Question 9

If a cell starts with $$2n = 6$$ chromosomes, how many DNA molecules are present in the cell at metaphase of mitosis?

Accepted Answer

$$12$$

Question 10

Which of the following is a key difference between spermatogenesis and oogenesis in animals?

Accepted Answer

Oogenesis produces one functional gamete and polar bodies, while spermatogenesis produces four functional gametes.

Question 11

A plant with genotype $$AaBb is $$self-crossed. What is the probability that an offspring will have the genotype $$AABB$$?

Accepted Answer

$$\frac{1}{16}$$

Question 12

Which of the following best describes the function of the kinetochore during cell division?

Accepted Answer

It attaches chromosomes to spindle microtubules, facilitating their movement.

Question 13

A researcher observes a 3:1 phenotypic ratio in the F2 generation of a monohybrid cross. Which of Mendel’s postulates does this observation support?

Accepted Answer

Segregation of unit factors

Question 14

Which stage of meiosis is responsible for reducing the chromosome number from diploid to haploid?

Accepted Answer

Anaphase I

Question 15

A human cell in G2 phase contains 46 chromosomes. How many chromatids are present in this cell?

Accepted Answer

$$92$$

Question 16

Which of the following scenarios would most likely result in a deviation from the expected Mendelian ratio in a dihybrid cross?

Accepted Answer

The two genes are located close together on the same chromosome (linked).

Question 17

In a chi-squared test, which formula is used to calculate the chi-squared value?

Accepted Answer

$$\$$chi^2$$ = \sum \frac{(O - E)^2$}{E}$$

Question 18

Which event during meiosis increases genetic variation among gametes?

Accepted Answer

Crossing over between homologous chromosomes during prophase I

Question 19

A woman is heterozygous for a gene ($$Aa) $$and her partner is homozygous recessive ($$aa). $$What is the probability that their child will be a heterozygote?

Accepted Answer

$$\frac{1}{2}$$

Question 20

Which of the following best describes the relationship between genotype and phenotype?

Accepted Answer

Genotype determines the set of alleles an organism has, which influences its observable traits (phenotype).

Genetics Exam 1 Study Guide: Genome Structure, Cell Division, and Mendelian Genetics

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