Question

an individual of a plant species shows a certain physical characteristic that requires two copies of the same allele to be expressed. based on this information, how would the allele for the characteristic most likely be classified?
a. recessive
b. dominant
c. sex - linked
d. polygenic

2 what is one important result of chromosomal crossing - over during meiosis?
a. an increase in the likelihood of having gametes in offspring that are genetically the same as their parents
b. an increase in the amount of genetic variation within a population that can improve its ability to survive
c. a decrease in the number of chromosome pairs that can be passed from each parent to its offspring
d. a decrease in the frequency of genetic mutations and a limit to the diversity of traits within a species

1. a specific genetic disorder is caused by nondisjunction. which statement describes how the genetic disorder occurs?

a. a problem with rna replication leads to gametes with extra proteins.
b. a problem with chromosome separation leads to gametes with damaged chromosomes.
c. incomplete dna replication leads to gametes with half the usual number of chromosomes.
d. incomplete chromosome separation leads to gametes with an abnormal number of chromosomes.

1. antibiotics are medicines that slow the growth of disease - causing bacteria. one of the ways the antibiotics work is by interfering with the normal functioning of bacterial ribosomes. how does this interference reduce the rate of bacterial reproduction?

a. by preventing the bacterial cell from synthesizing essential proteins
b. by increasing the rate at which bacterial cells go through the cell cycle
c. by blocking the bacterial cells access to nutrients from the host organism
d. by allowing harmful substances to enter the bacterial cell through its membrane

1. which sequence of events correctly describes the process of protein synthesis?

a. dna → transcription → mrna → translation → proteins produced
b. dna → translation → mrna → transcription → proteins produced
c. mrna → transcription → polypeptides form → translation → proteins produced
d. mrna → translation → polypeptides form → transcription → proteins produced

Explanation:

Question 21

A recessive allele is expressed only when two copies (homozygous recessive) are present. Dominant alleles are expressed with one copy. Sex - linked alleles are related to sex chromosomes, and polygenic traits are controlled by multiple genes. Since the characteristic requires two copies of the same allele, it's recessive.

Crossing - over during meiosis involves the exchange of genetic material between homologous chromosomes. This increases genetic variation in the population. Option A is wrong as crossing - over increases genetic differences from parents. Option C is wrong as it doesn't decrease chromosome pairs passed. Option D is wrong as it increases variation, not decreases mutations or limits traits.

Nondisjunction is the failure of chromosomes to separate properly during cell division (meiosis). This leads to gametes with an abnormal number of chromosomes. Option A is wrong as it's about RNA replication, not related to nondisjunction. Option B is wrong as it's about damaged chromosomes, not abnormal number. Option C is wrong as it's about DNA replication, not chromosome separation.

Answer:

A. Recessive

Question 22