The Cell Cycle
A cell has 10 chromosomes before S phase. How many chromosomes does it have after DNA replication?
10
What structure joins sister chromatids?
Centromere
Two organisms have the same gene at the same locus but different DNA versions. What are those versions called?
Alleles
What stage of meiosis involves crossing over?
Prophase I
What term describes an organism's genetic makeup?
Genotype
A cell's DNA is damaged before replication. Which checkpoint should prevent it from entering S phase?
G1
A cell's chromosomes align, but spindle fibers cannot attach to kinetochores. Which stage's chromosome separation is disrupted?
Anaphase
A species has 2n = 30. How many homologous pairs are present in a normal somatic cell?
15
Homologous chromosomes fail to separate in anaphase I. How many resulting gametes have abnormal chromosome numbers?
all 4
A dominant-phenotype plant crossed with aa produces recessive offspring. What is the unknown parent's genotype?
Aa (Heterozygous)
A cell completes DNA replication but fails its G2 checkpoint. What process should be delayed?
Mitosis
A cell has 8 chromosomes in G1. How many chromosomes are in each daughter cell after normal mitosis?
8
A species has n = 9. How many chromosomes should its normal zygote contain?
18
A cell has 2n = 6. How many tetrads form during prophase I?
3
Two carriers of an autosomal recessive disorder have a child. What is the probability the child is unaffected but a carrier?
50%
A mutation allows cells to ignore checkpoints and continue dividing. What condition can develop?
Cancer
A cell separates sister chromatids but fails cytokinesis. What is the immediate result?
one daughter cell containing two nuclei
What is the name for the specific location of a gene on a chromosome?
locus
A cell with 2n = 10 completes meiosis I. How many chromosomes and chromatids are in each daughter cell?
5 chromosomes and 10 chromatids
A carrier mother and unaffected father have a daughter. What is the probability the daughter is a carrier for the X-linked recessive trait?
50%
A cell with severely damaged DNA cannot repair it. What process can eliminate the cell?
Apoptosis
An animal cell cannot form an actin-myosin contractile ring. What process is directly disrupted?
Cytokinesis
Two genetically identical plants reproduce asexually. What is the main source of new heritable genetic differences between their descendants?
During meiosis, homologous chromosomes exchange DNA segments. What is the result?
Increased genetic variation through new combinations of alleles.
Two AaBb parents are crossed. Assuming independent assortment and complete dominance, what fraction of offspring show both recessive traits?
1/16