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BIO 235 Exam 1 With 100% Correct Answers 2025/2026, Exams of Biology

While undergoing mitosis, the ____ is the central regio on DNA that connects sister chromatids - Correct Answer-Centromere Homologous chromosome pairs...? - Correct Answer-have a chromosome from mother and father, synapse during prophase of meiosis 1, same genes but different alleles, pair of sister chromatids during prophase meiosis 1 What stage of the cell cycle does DNA replication occur in preparation for division? - Correct Answer-S phase What is one defining difference between DNA of G2 and G1 phases of the cell cycle? - Correct Answer-G2 nucleus has 2 copies of each chromosome How many centromeres exist in the G1 phase of a diploid organism with 24 chromosomes? - Correct Answer-24

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BIO 235 Exam 1 With 100% Correct
Answers 2025/2026
While undergoing mitosis, the ____ is the central regio on DNA that connects sister
chromatids - Correct Answer-Centromere
Homologous chromosome pairs...? - Correct Answer-have a chromosome from mother
and father, synapse during prophase of meiosis 1, same genes but different alleles, pair
of sister chromatids during prophase meiosis 1
What stage of the cell cycle does DNA replication occur in preparation for division? -
Correct Answer-S phase
What is one defining difference between DNA of G2 and G1 phases of the cell cycle? -
Correct Answer-G2 nucleus has 2 copies of each chromosome
How many centromeres exist in the G1 phase of a diploid organism with 24
chromosomes? - Correct Answer-24
A mammal's gametes contain 24 chromosomes (1n=24) how many chromosomes
would we expect to find in its adult (somatic) cells? - Correct Answer-48
Meiosis 2 results in a reduction, or halving of the number of chromosomes in each
daughter cell. - Correct Answer-False
List 2 of the mechanisms discussed in class by which meiosis produces genetic
variation - Correct Answer-1.random orientation/distribution of homologous
chromosomes in anaphase 1
2. crossing over
What is a bivalent? - Correct Answer-a pair of homologous chromosomes which consist
of sister chromatids
How many chromatids are in 4 bivalents? - Correct Answer-16
In meiosis, ___ separate during meiosis 1, and ___ separate during meiosis 2 - Correct
Answer-homologous pairs, sister chromatids
When an allele masks another allele in a heterozygote, preventing expression of the
masked allele, this allele can be described as? - Correct Answer-dominant
In plants, meiosis results in an entire haploid _____ generation from the diploid _____
generation - Correct Answer-gametophyte, sporophyte
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BIO 235 Exam 1 With 100% Correct

Answers 2025/2 026

While undergoing mitosis, the ____ is the central regio on DNA that connects sister chromatids - Correct Answer-Centromere Homologous chromosome pairs...? - Correct Answer-have a chromosome from mother and father, synapse during prophase of meiosis 1, same genes but different alleles, pair of sister chromatids during prophase meiosis 1 What stage of the cell cycle does DNA replication occur in preparation for division? - Correct Answer-S phase What is one defining difference between DNA of G2 and G1 phases of the cell cycle? - Correct Answer-G2 nucleus has 2 copies of each chromosome How many centromeres exist in the G1 phase of a diploid organism with 24 chromosomes? - Correct Answer- 24 A mammal's gametes contain 24 chromosomes (1n=24) how many chromosomes would we expect to find in its adult (somatic) cells? - Correct Answer- 48 Meiosis 2 results in a reduction, or halving of the number of chromosomes in each daughter cell. - Correct Answer-False List 2 of the mechanisms discussed in class by which meiosis produces genetic variation - Correct Answer-1.random orientation/distribution of homologous chromosomes in anaphase 1

  1. crossing over What is a bivalent? - Correct Answer-a pair of homologous chromosomes which consist of sister chromatids How many chromatids are in 4 bivalents? - Correct Answer- 16 In meiosis, ___ separate during meiosis 1, and ___ separate during meiosis 2 - Correct Answer-homologous pairs, sister chromatids When an allele masks another allele in a heterozygote, preventing expression of the masked allele, this allele can be described as? - Correct Answer-dominant In plants, meiosis results in an entire haploid _____ generation from the diploid _____ generation - Correct Answer-gametophyte, sporophyte

How many ova, or mature egg cells will develop from one oogonia? - Correct Answer- 1 How is it possible for X and Y sex chromosomes to pair, even though they are non homologous? - Correct Answer-the PAR region offers short areas homology to pair with The inactivated X chromosome in females becomes heterochromatin and is visible as? - Correct Answer-Barr body How do female cells balance the amount of protein produced by X-linked genes in males and females? - Correct Answer-X-inactivation How are birds sex chromosomes different between male and females, compared to mammals? - Correct Answer-the male has 2 Z chromosomes making them homogametic and the female has one Z and one W chromosome making them heterogametic hemizygous - Correct Answer-A gene present on the X chromosome that is expressed in males in both the recessive and dominant condition Can we determine the genotype of the offspring of 2 parents with a heterozygous incomplete dominance trait based off the phenotypes alone? What would we expect the phenotypic ratio to be? - Correct Answer-Yes; the ration will be 1:2: We know color blindness is a recessive x-linked trait. Are males or females more susceptible to color blindness? - Correct Answer-males If a color blind mother and normal sighted father have children, what is the probability that a male will be color blind? What is the probability of having 2 children that are colorblind? - Correct Answer-100%, 25% A recessive trait...? - Correct Answer-requires both parents to have at least one copy for the trait to be expressed in the progeny, masked in heterozygotes, and should see a 1/ probability of appearing from heterozygote parents We can deduce the genotype of F1 offspring from the phenotype alone if the parents are heterozygous. - Correct Answer-false List/describe the 2 things that only occur in prophase 1 of meiosis 1. - Correct Answer-

  1. crossing over
  2. synapsing between homologous chromosomes law of independent assortment - Correct Answer-the law that states that genes separate independently of one another in meiosis

How many chromosomes will be found in a human secondary spermatocyte? - Correct Answer- 23 In birds and reptiles, males are homogametic. - Correct Answer-true Which ratio suggests a dominant epistatic interaction between 2 genes? - Correct Answer-12:3: What is a polar body? - Correct Answer-small secondary oocytes which are eventually degraded 2 individuals with a genetic defect known to be caused by mutations on 2 separate genes have several children. None of the children are affected by the defect at all. What could be said about the mutations of the 2 parents? - Correct Answer-they are complimentary If a diploid organism has 46 chromosomes, how many chromosomes will be present during the S phase of interphase? - Correct Answer- 46 Cells in this phase are post-mitotic and will no longer divide - Correct Answer-telophase