1.
Two black guinea pigs bred and produced 3 black offspring and 2 albino offspring. Assuming no mutations, which guinea pigs must be heterozygous?
Correct Answer
D. Both parents
Explanation
Both parents must be heterozygous because in order for the black guinea pigs to produce both black and albino offspring, they must carry the recessive albino allele. This means that both parents have at least one copy of the albino allele, making them heterozygous for the black coat color gene.
2.
Which example best illustrates Mendel's law of independent assortment?
Correct Answer
C. A tall purple-flowered pea plant and a short white-flowered pea plant are crossed, producing offspring including tall white-flowered pea plants.
Explanation
The example of crossing a tall purple-flowered pea plant with a short white-flowered pea plant and producing offspring including tall white-flowered pea plants best illustrates Mendel's law of independent assortment. This is because the traits of height (tall or short) and flower color (purple or white) are independently inherited and can be combined in different combinations in the offspring. The fact that the offspring include tall plants with white flowers demonstrates the independent assortment of these traits.
3.
The manner in which chromosomes separate into gametes during meiosis is the molecular mechanism behind which of Mendel's laws, if either?
Correct Answer
C. Both the law of independent assortment and the law of segregation
Explanation
During meiosis, chromosomes separate and are randomly distributed into gametes. This process is known as the law of independent assortment, as it explains how different traits are inherited independently of each other. Additionally, the separation of homologous chromosomes during meiosis is the basis of the law of segregation, which states that each gamete receives only one copy of each chromosome. Therefore, the correct answer is that both the law of independent assortment and the law of segregation are explained by the manner in which chromosomes separate during meiosis.
4.
Which event of meiosis reveals the mechanism for understanding Mendel's law of segregation and independent assortment?
Correct Answer
B. The arrangement of homologous chromosomes during metapHase I varies from cell to cell.
Explanation
The arrangement of homologous chromosomes during metaphase I varies from cell to cell. This event of meiosis is important for understanding Mendel's law of segregation and independent assortment because it allows for the random alignment and separation of homologous chromosomes. This random alignment leads to the independent assortment of alleles, which is a key principle in Mendelian genetics. The variation in the arrangement of homologous chromosomes during metaphase I ensures genetic diversity in the resulting gametes, which is essential for the inheritance of traits according to Mendel's laws.
5.
The passing of traits from parents to offspring is called
Correct Answer
B. Heredity.
Explanation
Heredity refers to the passing of traits from parents to offspring. It involves the transmission of genetic information from one generation to the next, which determines the characteristics and traits that an individual inherits. This process is responsible for the similarities and resemblances observed between family members and is a fundamental concept in the field of genetics.
6.
The law of segregation states that
Correct Answer
A. Alleles of a gene separate from each other during meiosis.
Explanation
The law of segregation states that alleles of a gene separate from each other during meiosis. This means that when gametes (sperm and egg cells) are formed, each gamete will only receive one allele for each gene. This is because during meiosis, the pairs of homologous chromosomes separate, and each resulting gamete receives only one copy of each chromosome. As a result, different alleles of a gene can be found in different gametes, allowing for genetic variation and inheritance of traits.
7.
A punnett square shows all of the following EXCEPT
Correct Answer
D. The actual results of a genetic cross.
Explanation
A punnett square is a diagram used to predict the possible outcomes of a genetic cross between two individuals. It shows the genotypes of the offspring by combining the alleles from each parent's gametes. However, it does not show the actual results of a genetic cross, as those can vary due to chance and other factors.
8.
In humans, having freckles (F) is dominant to not having freckles (f). The inheritance of these traits can be studied using a Punnett square similar to the one shown below.Refer to the illustration above. The child represented in box 1 in the Punnett square would
Correct Answer
A. Be homozygous for freckles.
Explanation
The child represented in box 1 in the Punnett square would be homozygous for freckles because both of its alleles for the freckles trait are dominant (F). Homozygous means having two identical alleles for a particular trait, in this case, both alleles being dominant (F). Therefore, the child will have freckles.
9.
Refer to the illustration above. Which box in the Punnett square represents a child who does NOT have freckles?
Correct Answer
D. Box 4
Explanation
Box 4 represents a child who does not have freckles because it is the only box that contains two lowercase letters for the freckles trait. According to the rules of genetics, freckles are a dominant trait, represented by an uppercase letter. Since box 4 only contains lowercase letters, it means that both alleles for freckles are recessive, resulting in a child without freckles.
10.
Refer to the illustration above. The child in box 3 of the Punnett square has the genotype
Correct Answer
B. Ff
Explanation
The child in box 3 of the Punnett square has the genotype Ff. This is because the child inherited one dominant allele (F) from one parent and one recessive allele (f) from the other parent. The dominant allele (F) masks the expression of the recessive allele (f), resulting in the child having the heterozygous genotype Ff.
11.
Linked genes
Correct Answer
C. Are on the same chromosome.
Explanation
Linked genes refer to genes that are located on the same chromosome. These genes tend to be inherited together and are less likely to separate during the process of genetic recombination. This is because they are physically close to each other on the same chromosome and are thus more likely to be inherited as a unit. Therefore, the correct answer is that linked genes are on the same chromosome.
12.
When Gregor Mendel crossed a tall plant with a short plant, the F1 plants inherited
Correct Answer
B. An allele for tallness from the tall parent and an allele for shortness from the short parent.
Explanation
When Gregor Mendel crossed a tall plant with a short plant, the F1 plants inherited an allele for tallness from the tall parent and an allele for shortness from the short parent. This is because the trait for tallness is dominant, while the trait for shortness is recessive. Therefore, the F1 plants will exhibit the dominant trait of tallness, but they will also carry the recessive allele for shortness.
13.
In the P generation, a tall plant is crossed with a short plant. The probability that an F2 plant will be tall is
Correct Answer
B. 75%
Explanation
When a tall plant is crossed with a short plant in the P generation, the resulting F1 generation will all be tall plants because tallness is dominant over shortness. When the F1 generation plants are crossed with each other in the F2 generation, the Punnett square shows that there is a 3:1 ratio of tall to short plants. This means that there is a 75% probability that an F2 plant will be tall.
14.
Complete a punnett square for a heterozygous tall plant crossed with a homozygous tall plant. Which of the following is true about the offspring resulting from the cross?
Correct Answer
C. All are expected to be tall.
Explanation
When a heterozygous tall plant (Tt) is crossed with a homozygous tall plant (TT), the Punnett square shows that all of the offspring will inherit a dominant allele for tallness (T) from either parent. Therefore, all of the offspring are expected to be tall.
15.
In rabbits, black fur (B) is dominant to brown fur (b). Consider the following cross between two rabbits.Refer to the illustration above. The device shown, which is used to determine the probably outcome of genetic crosses, is called a
Correct Answer
B. Punnett square.
Explanation
A Punnett square is a tool used to determine the possible outcomes of genetic crosses. It is a square grid that is used to organize and visualize the different combinations of alleles that can be passed on from parents to offspring. In this case, since the question is about the inheritance of fur color in rabbits, the Punnett square would be the appropriate device to use to determine the probable outcome of the cross between the two rabbits.
16.
In rabbits, black fur (B) is dominant to brown fur (b). Consider the following cross between two rabbits.Refer to the illustration above. Both of the parents in the cross are
Correct Answer
A. Black.
Explanation
The given answer is black because it is stated in the question that black fur (B) is dominant to brown fur (b). Since both parents are black, they must have the dominant allele for black fur (BB or Bb). Therefore, their offspring will also have black fur.
17.
In rabbits, black fur (B) is dominant to brown fur (b). Consider the following cross between two rabbits.Refer to the illustration above. The phenotype of the offspring indicated by box 3 would be
Correct Answer
B. Black.
Explanation
In this scenario, the question states that black fur (B) is dominant to brown fur (b) in rabbits. Since the phenotype of the offspring indicated by box 3 is not specified, we can assume that both parent rabbits carry the genotype Bb (one black allele and one brown allele). When these two rabbits are crossed, there is a 25% chance of producing offspring with the genotype BB (black fur), a 50% chance of producing offspring with the genotype Bb (black fur), and a 25% chance of producing offspring with the genotype bb (brown fur). Therefore, the most likely phenotype of the offspring indicated by box 3 would be black.