1.
Which type of reproduction produces the most variation.
Correct Answer
A. Sexual
Explanation
Sexual reproduction produces the most variation because it involves the fusion of genetic material from two different individuals, resulting in offspring with a combination of traits from both parents. This genetic recombination during sexual reproduction leads to increased genetic diversity and variation within a population. In contrast, asexual reproduction involves the production of offspring that are genetically identical or very similar to the parent, resulting in less variation. Homosexual reproduction is not a recognized type of reproduction, and "none of the above" is not a valid option as sexual reproduction is known to produce the most variation.
2.
How many alleles are present for one trait in normal
cells?
Correct Answer
B. 2
Explanation
In normal cells, there are typically two alleles present for one trait. Alleles are alternate forms of a gene that can occupy the same gene locus on a chromosome. Each individual inherits one allele from each parent, resulting in a pair of alleles for a particular trait. This is known as diploidy, and it allows for genetic diversity and the possibility of different phenotypes.
3.
Which one of the following represents a genotype?
Correct Answer
C. Bb
Explanation
The given answer "Bb" represents a genotype because it represents the combination of alleles for a specific trait. In this case, "B" and "b" represent different versions of the gene for eye color, and "Bb" indicates that the individual has one copy of each allele. The genotype determines the physical characteristics or traits that an individual will have.
4.
Which one of the following represents a phenotype?
Correct Answer
A. Blue eyes
Explanation
A phenotype refers to the observable physical or biochemical characteristics of an organism, which are determined by its genetic makeup or genotype. Blue eyes is a specific physical trait that can be observed in an individual, making it a clear example of a phenotype.
5.
In the following cross Tt x Tt, what chance will
the offspring have of being tt?
Correct Answer
C. 25%
Explanation
When crossing two individuals with the genotype Tt, there is a 25% chance that the offspring will have the genotype tt. This is because each parent can pass on either a T or a t allele, resulting in four possible combinations: TT, Tt, tT, and tt. Out of these four combinations, only one includes the tt genotype, which is why the chance is 25%.
6.
If blue eyes is recessive and a person has blue eyes, then
the trait is…
Correct Answer
C. Pure
Explanation
If blue eyes is recessive and a person has blue eyes, it means that both of their parents must have the blue eye gene as well. Since blue eyes is a recessive trait, it can only be expressed when an individual has two copies of the blue eye gene. This suggests that the person with blue eyes has a pure genotype for blue eyes, meaning they do not carry any dominant alleles for eye color. Therefore, the trait of having blue eyes in this case is considered pure.
7.
Which of the following genotypes is hybrid for a single
trait?
Correct Answer
D. Bb
Explanation
A genotype is considered hybrid when it contains two different alleles for a single trait. In this case, the genotype Bb is hybrid because it contains one dominant allele (B) and one recessive allele (b) for the trait. The other genotypes listed (BB, BBtt, bbtt) are not hybrid because they either have two dominant alleles or two recessive alleles for the trait.
8.
Which of the following is true about alleles?
Correct Answer
B. Each allele in a pair may carry different information.
Explanation
Alleles are alternative forms of a gene that occupy the same position on a specific chromosome. They can exist in pairs, with one allele inherited from each parent. Each allele in a pair may carry different information because they can have different variations or mutations that result in different traits or characteristics. This allows for genetic diversity and variation within a population.
9.
Which one of these is a possible sex cell produced by
TtRR?
Correct Answer
C. TR
Explanation
A possible sex cell produced by TtRR could be tR. This is because TtRR indicates that the individual has one allele for tall (T) and one for short (t), and two alleles for red (R). When producing sex cells, each parent randomly passes on one allele for each trait. Therefore, the individual could produce a sex cell with the allele for short (t) and the allele for red (R), resulting in the combination tR.
10.
If B = Brown eyes and b=blue eyes, what are the odds that a child whose parents are Bb x Bb will have brown eyes?
Correct Answer
B. 75%
Explanation
The odds that a child whose parents are Bb x Bb will have brown eyes is 75%. This is because the parents each have one dominant allele for brown eyes (B) and one recessive allele for blue eyes (b). When they have a child, there is a 25% chance that the child will inherit two recessive alleles (bb) and have blue eyes, and a 75% chance that the child will inherit at least one dominant allele (Bb or BB) and have brown eyes.