Question

1.4.2 test (cst): heredity
question 20 of 25
examine the model.
which statement best describes the source of genetic variation shown in the
model?
a. random chromosomes move to opposite sides of a cell to form
daughter cells through a process called crossing over.
b. chromosomes are duplicated at the start of prophase to ensure
that all daughter cells receive identical copies of the genetic
material.
c. two haploid gametes combine chromosomes to form a diploid
zygote cell.
d. tetrads line up randomly and are then pulled apart, resulting in
different combinations of maternal and paternal chromosomes.

Explanation:

Step1: Analyze Option A

Crossing - over occurs in prophase I, not the random movement of chromosomes in anaphase I as described in option A.

Step2: Analyze Option B

Chromosome duplication occurs before meiosis (not just at the start of prophase I), and the process shown in the model (anaphase I) is about chromosome separation, not ensuring identical copies.

Step3: Analyze Option C

The model shows meiosis (a single - cell process), not fertilization (combination of two gametes).

Step4: Analyze Option D

In anaphase I of meiosis, tetrads (homologous chromosome pairs) line up randomly (independent assortment) and then are pulled apart. This random alignment and separation result in different combinations of maternal and paternal chromosomes in the daughter cells, which is a source of genetic variation.

Answer:

D. Tetrads line up randomly and are then pulled apart, resulting in different combinations of maternal and paternal chromosomes.