Question 1

Which of the following best explains why meiosis, but not mitosis, leads to increased genetic variation in sexually reproducing organisms?

Accepted Answer

Meiosis includes independent assortment and crossing over, which shuffle alleles between homologous chromosomes.

Question 2

A patient is diagnosed with a tumor that does not invade surrounding tissues or spread to other parts of the body. Which term best describes this tumor?

Accepted Answer

Benign

Question 3

During which phase of the cell cycle does DNA replication occur, and what is the result of this process?

Accepted Answer

S phase; each chromosome is duplicated to form sister chromatids.

Question 4

A cell with a diploid number of $$2n = 8$$ undergoes meiosis. How many chromosomes will each resulting gamete contain?

Accepted Answer

$$4$$

Question 5

Which of the following scenarios best illustrates Mendel’s Law of Segregation?

Accepted Answer

A plant with genotype $$Aa$$ produces gametes, half carrying $$A$$ and half carrying $$a.$$

Question 6

A woman who is heterozygous for a recessive genetic disorder ($$Dd) $$and a man who is homozygous dominant ($$DD) $$have a child. What is the probability that their child will be a carrier of the disorder?

Accepted Answer

$$50\%$$

Question 7

Which of the following best describes the structure of a DNA molecule?

Accepted Answer

A double helix with a sugar-phosphate backbone and nitrogenous base pairs held together by hydrogen bonds.

Question 8

If a DNA sequence is $$5'	ext{-}ATGCGTACG-3'$$, what would be the complementary DNA strand produced during replication?

Accepted Answer

$$3'	ext{-}TACGCATGC-5'$$

Question 9

A mutation changes the DNA sequence from $$5'	ext{-}ATG\,GCC\,TAA-3' to$$ $$5'	ext{-}ATG\,GCA\,TAA-3'. $$What type of mutation is this, and what is its likely effect?

Accepted Answer

Substitution; may result in a different amino acid in the protein.

Question 10

Which of the following best explains why nondisjunction during meiosis can lead to Down syndrome?

Accepted Answer

It results in an extra copy of chromosome 21 in the gamete, leading to trisomy 21 after fertilization.

Question 11

Which process is responsible for the separation of sister chromatids during mitosis, and in which stage does this occur?

Accepted Answer

Chromatid separation; anaphase

Question 12

A pedigree shows a trait that appears in every generation and affects both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 13

Which of the following statements about the central dogma of molecular biology is correct?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 14

A man with blood type $$AB$$ and a woman with blood type $$O$$ have a child. Which blood types are possible for their child?

Accepted Answer

Only type $$A or $$type $$B$$

Question 15

Which of the following best describes the difference between a gene and an allele?

Accepted Answer

A gene is a specific sequence of DNA that codes for a trait, while an allele is a variant form of that gene.

Question 16

Which of the following is a real-world example of codominance in humans?

Accepted Answer

A person with type $$AB$$ blood expressing both $$A$$ and $$B$$ antigens equally.

Question 17

During translation, which molecule brings amino acids to the ribosome according to the codon sequence on the mRNA?

Accepted Answer

tRNA

Question 18

A cell is observed to have uncontrolled growth and the ability to invade other tissues. Which of the following best explains the underlying cause?

Accepted Answer

Loss of cell cycle control leading to malignant tumor formation and metastasis.

Question 19

Which of the following best explains why a frameshift mutation is often more harmful than a substitution mutation?

Accepted Answer

A frameshift mutation changes the reading frame, altering every amino acid downstream of the mutation.

Question 20

Which of the following statements about the difference between DNA and RNA is correct?

Accepted Answer

DNA contains deoxyribose sugar and thymine, while RNA contains ribose sugar and uracil.

Cellular Reproduction, Genetics, and DNA: Study Guide for General Biology

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