Q: A testcross is performed to determine the genotype of a pea plant with a dominant phenotype. Which of the following crosses is correct for a testcross?

Dominant phenotype individual $$\times$$ homozygous recessive individual

Question 1

Which of the following best describes Mendel's Law of Segregation?

Accepted Answer

The two alleles for a heritable character separate during gamete formation and end up in different gametes.

Question 2

A pea plant with genotype $$Tt ($$where $$T is $$tall and $$t is $$dwarf) is crossed with a dwarf plant ($$tt). $$What is the expected phenotypic ratio of the offspring?

Accepted Answer

1 tall : 1 dwarf

Question 3

In a dihybrid cross between two heterozygous pea plants ($$RrYy 	imes RrYy$$), what is the expected phenotypic ratio among the offspring?

Accepted Answer

$$9:3:3:1$$

Question 4

Which of the following statements about alleles is correct?

Accepted Answer

Alleles are different forms of a gene found at the same locus on homologous chromosomes.

Question 5

A testcross is performed to determine the genotype of a pea plant with a dominant phenotype. Which of the following crosses is correct for a testcross?

Accepted Answer

Dominant phenotype individual $$	imes$$ homozygous recessive individual

Question 6

If a trihybrid cross is performed between two individuals heterozygous for three traits ($$AaBbCc 	imes AaBbCc$$), how many different types of gametes can each parent produce?

Accepted Answer

$$8$$

Question 7

Which of the following best explains why Mendel's work was not recognized until 1900?

Accepted Answer

The scientific community lacked the technology to observe chromosomal behavior during meiosis.

Question 8

A couple has a child with albinism, a recessive trait. Neither parent is albino. What is the probability that their next child will also have albinism?

Accepted Answer

$$\frac{1}{4}$$

Question 9

Which of the following is a key advantage of the forked-line method over the Punnett square for predicting genotypes in crosses involving three or more traits?

Accepted Answer

It simplifies the calculation by breaking down the problem into a series of monohybrid crosses.

Question 10

In a pedigree, a filled square represents:

Accepted Answer

An affected male

Question 11

The chromosomal theory of inheritance states that:

Accepted Answer

Genes are located on chromosomes, which are transmitted from generation to generation.

Question 12

If the haploid number ($$n) of a $$species is 4, how many different possible gametes can be formed due to independent assortment?

Accepted Answer

$$2^4 = 16$

Question 13

Which of the following is the correct formula for calculating the degrees of freedom ($$df) in a $$chi-square ($$\$$chi^2$$) analysis?

Accepted Answer

$$df = n - 1$$

Question 14

A monohybrid cross between two heterozygous individuals ($$Aa 	imes Aa) $$produces which genotypic ratio among the offspring?

Accepted Answer

$$1:2:1$$

Question 15

Which of the following best describes a homozygous genotype?

Accepted Answer

An individual with two identical alleles for a gene

Question 16

In a real-world scenario, a genetic counselor uses a pedigree to predict the risk of a child inheriting a genetic disorder. What is the main purpose of using a pedigree in this context?

Accepted Answer

To analyze inheritance patterns and assess the probability of a trait appearing in future generations

Question 17

Which of the following is NOT one of Mendel's postulates?

Accepted Answer

Genes are located on mitochondria.

Question 18

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

Accepted Answer

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

Question 19

Which of the following best explains the purpose of chi-square ($$\$$chi^2$$) analysis in genetics?

Accepted Answer

To determine whether observed genetic ratios deviate significantly from expected ratios due to chance

Question 20

In humans, the diploid number is 46. How many chromosomes are present in a human gamete?

Accepted Answer

23

Mendelian Genetics: Principles of Transmission Genetics

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