Trivia Quiz On Genetics Revision

1. What is a dominant allele?

A dormant gene that is never expressed

The allele that will always be expressed if present

The allele that will only be expressed if there are two present

A dominant allele is an allele that will always be expressed if it is present. This means that even if there is only one copy of the dominant allele in an individual's genetic makeup, it will still be expressed and override the effects of any other alleles that may be present.

Explanation

A dominant allele is an allele that will always be expressed if it is present. This means that even if there is only one copy of the dominant allele in an individual's genetic makeup, it will still be expressed and override the effects of any other alleles that may be present.

2. If blue eye colour (e) is recessive to brown eyes (B), what is the genotype of a purebred brown eyed person

BB

Bb

A purebred brown eyed person would have the genotype BB. This means that both of their alleles for eye color are brown (B), and they do not carry the recessive blue eye color allele (e). Since brown eye color is dominant over blue eye color, a person with the genotype BB will always have brown eyes.

Explanation

A purebred brown eyed person would have the genotype BB. This means that both of their alleles for eye color are brown (B), and they do not carry the recessive blue eye color allele (e). Since brown eye color is dominant over blue eye color, a person with the genotype BB will always have brown eyes.

3. What is a phenotype?

The genetic code for a trait

The physical expression of a trait

A new type of pen

The original cell of an organism

A phenotype refers to the physical expression of a trait. It is the observable characteristics or traits of an organism that are determined by its genetic code. This includes traits such as eye color, height, and hair type. The phenotype is influenced by both genetic factors and environmental factors, and it can vary among individuals within a population.

Explanation

A phenotype refers to the physical expression of a trait. It is the observable characteristics or traits of an organism that are determined by its genetic code. This includes traits such as eye color, height, and hair type. The phenotype is influenced by both genetic factors and environmental factors, and it can vary among individuals within a population.

4. How many chromosomes are present in the zygote from which a human grows

12

23

46

92

The zygote from which a human grows contains 46 chromosomes. Chromosomes are thread-like structures that carry genetic information and are found in the nucleus of cells. In humans, each parent contributes 23 chromosomes, resulting in a total of 46 chromosomes in the zygote. These chromosomes contain the DNA that determines an individual's traits and characteristics.

Explanation

The zygote from which a human grows contains 46 chromosomes. Chromosomes are thread-like structures that carry genetic information and are found in the nucleus of cells. In humans, each parent contributes 23 chromosomes, resulting in a total of 46 chromosomes in the zygote. These chromosomes contain the DNA that determines an individual's traits and characteristics.

5. How many chromosomes are contained in the sperm of a human?

12

23

46

92

The correct answer is 23 because human sperm cells contain half the number of chromosomes compared to other human cells. This is because during fertilization, the sperm cell fuses with an egg cell, which also contains 23 chromosomes, resulting in a total of 46 chromosomes in the resulting zygote.

Explanation

The correct answer is 23 because human sperm cells contain half the number of chromosomes compared to other human cells. This is because during fertilization, the sperm cell fuses with an egg cell, which also contains 23 chromosomes, resulting in a total of 46 chromosomes in the resulting zygote.

6. What are the components that make up the structure of DNA

Meiosis and Mitosis

A, T, C

Phosphate group, pentose sugar, nitrogen base

Cell, nucleous, membrane

The correct answer is "Phosphate group, pentose sugar, nitrogen base." These three components are the building blocks of DNA. The phosphate group and pentose sugar (deoxyribose) form the backbone of the DNA molecule, while the nitrogen bases (adenine, thymine, cytosine, and guanine) pair up to form the rungs of the DNA ladder. Together, these components create the structure of DNA, which is essential for storing and transmitting genetic information.

Explanation

The correct answer is "Phosphate group, pentose sugar, nitrogen base." These three components are the building blocks of DNA. The phosphate group and pentose sugar (deoxyribose) form the backbone of the DNA molecule, while the nitrogen bases (adenine, thymine, cytosine, and guanine) pair up to form the rungs of the DNA ladder. Together, these components create the structure of DNA, which is essential for storing and transmitting genetic information.

7. If blue eye colour (e) is recessive to brown eyes (B) and two heterozygous parents have a child, what is the chance that the childs phenotype will be blue eyed? *Hint* Try a Punnett square.

100%

75%

50%

25%

When two heterozygous parents (Bb) have a child, there is a 25% chance that the child will have a blue eye phenotype. This can be determined using a Punnett square, where the possible genotypes of the child are BB, Bb, Bb, and bb. The bb genotype represents the blue eye phenotype, and since there is only one out of the four possible genotypes that results in blue eyes, the chance is 25%.

Explanation

When two heterozygous parents (Bb) have a child, there is a 25% chance that the child will have a blue eye phenotype. This can be determined using a Punnett square, where the possible genotypes of the child are BB, Bb, Bb, and bb. The bb genotype represents the blue eye phenotype, and since there is only one out of the four possible genotypes that results in blue eyes, the chance is 25%.

8. If blue eye colour (b) is recessive to brown eyes (B), what would be the genotype of a brown eyed person?

Bb or BB

Bb or Bb

Since brown eyes (B) are dominant over blue eyes (b), a person with brown eyes can have either one or two dominant alleles. A genotype of BB means they have two dominant alleles, while a genotype of Bb means they have one dominant and one recessive allele. Both genotypes result in brown eyes because the dominant allele (B) will express the brown eye color.

Explanation

Since brown eyes (B) are dominant over blue eyes (b), a person with brown eyes can have either one or two dominant alleles. A genotype of BB means they have two dominant alleles, while a genotype of Bb means they have one dominant and one recessive allele. Both genotypes result in brown eyes because the dominant allele (B) will express the brown eye color.