Cell Division Basics
Why do cells divide?
Growth, repair, replacement of old cells, and reproduction.
What happens during the S phase?
DNA is replicated.
During which phase do chromosomes line up in the center of the cell?
Metaphase
What is the difference between genotype and phenotype?
Genotype is the genetic makeup; phenotype is the observable characteristic.
What is incomplete dominance?
A pattern of inheritance where the heterozygous phenotype is a blend of the two parental traits.
What are daughter cells?
The new cells produced from cell division.
Which phases make up interphase?
G1, S, and G2.
What happens to sister chromatids during anaphase?
They separate and move to opposite poles.
What does heterozygous mean?
Having two different alleles for a trait.
What is codominance?
A pattern of inheritance where both alleles are fully expressed.
Why must DNA be copied before cell division?
So each daughter cell receives a complete set of genetic information.
What is the role of spindle fibers?
They move chromosomes during mitosis.
Put the phases of mitosis in the correct order.
Prophase → Metaphase → Anaphase → Telophase.
Two heterozygous pea plants (Yy × Yy) are crossed. What is the phenotypic ratio?
3 yellow : 1 green.
Why is blood type considered an example of multiple alleles?
Because there are three alleles involved: IA, IB, and i.
What happens to chromosome number during mitosis?
The chromosome number stays the same.
What is a checkpoint in the cell cycle?
A control point that determines whether a cell can continue to the next stage.
What happens to the nuclear membrane during telophase?
It reforms around each set of chromosomes.
Tall (T) is dominant over short (t). A heterozygous tall plant (Tt) is crossed with a short plant (tt). What percentage of offspring will be short?
50%.
A heterozygous Type A parent (IAi) and a heterozygous Type B parent (IBi) have children. What is the probability of Type O blood?
25%.
Why are daughter cells smaller than the parent cell at first, and what is the advantage?
The cytoplasm is divided between two cells, making them smaller. This gives them a higher surface area-to-volume ratio, allowing materials to move in and out more efficiently.
What happens if a cell does not receive the "go" signal at the G1 checkpoint?
It enters the G0 phase.
Why is anaphase important?
It ensures chromosomes are equally distributed to the daughter cells.
Two heterozygous black guinea pigs (Bb × Bb) are crossed. What are the genotypic and phenotypic ratios?
Why does eye color have many shades instead of only one dominant and one recessive phenotype?
Because eye color is controlled by multiple genes (polygenic inheritance).