Part 3

Question 1

Mendel’s monohybrid cross

Answer 1

Cross tracking one trait; reveals law of segregation.

Question 2

Mendel’s dihybrid cross

Answer 2

Cross tracking two traits; reveals law of independent assortment.

Question 3

Dominant vs recessive

Answer 3

Dominant alleles mask recessive alleles in heterozygotes.

Question 4

Homozygous vs heterozygous

Answer 4

Homozygous: two identical alleles; heterozygous: two different alleles.

Question 5

Punnett square purpose

Answer 5

Predicts offspring genotypes and phenotypes.

Question 6

How to read a pedigree

Answer 6

Squares = males; circles = females; shading = affected.

Question 7

Barr body

Answer 7

Inactivated X chromosome in female cells.

Question 8

Chromosome mutations

Answer 8

Deletion, duplication, inversion, translocation.

Question 9

Linkage disequilibrium

Answer 9

Genes close together on the same chromosome are inherited together.

Question 10

Directionality of DNA

Answer 10

Strands run 5’ → 3’; polymerase adds nucleotides to 3’ end.

Question 11

Base pairing rules

Answer 11

A–T with 2 H-bonds; G–C with 3 H-bonds.

Question 12

Role of helicase

Answer 12

Unwinds DNA at the replication fork.

Question 13

Role of primase

Answer 13

Synthesizes RNA primers needed to start DNA replication.

Question 14

Role of DNA polymerase I

Answer 14

Removes RNA primers and replaces them with DNA.

Question 15

Role of DNA ligase

Answer 15

Seals nicks, joining Okazaki fragments.

Question 16

Start codon

Answer 16

AUG (codes for methionine).

Question 17

Stop codons

Answer 17

UAA, UAG, UGA.

Question 18

5’ cap purpose

Answer 18

Protects mRNA and helps ribosome binding.

Question 19

Poly-A tail purpose

Answer 19

Stabilizes mRNA and controls nuclear export.

Question 20

Splicing definition

Answer 20

Removal of introns; exons retained and joined.

Question 21

Introns advantage

Answer 21

Allow alternative splicing → protein diversity.

Question 22

Translation sites

Answer 22

A (aminoacyl), P (peptidyl), E (exit).

Question 23

Histone acetylation effect

Answer 23

Loosens chromatin → increased transcription.

Question 24

Enhancer

Answer 24

Regulatory DNA sequence activating transcription from a distance.

Question 25

DNA methylation effect

Answer 25

Silences genes; tighter chromatin.

Question 26

Gene cloning

Answer 26

Insert DNA into plasmid, transform bacteria, select with markers.

Question 27

Stem cell properties

Answer 27

Self‑renewal & ability to differentiate.

Question 28

Two types of stem cells

Answer 28

Embryonic (pluripotent) & adult (multipotent).

Question 29

CRISPR function

Answer 29

Cas9 uses guide RNA to cut DNA at specific sequences.

Question 30

PCR purpose

Answer 30

Amplify DNA sequence exponentially.

Question 31

Gel electrophoresis use

Answer 31

Separates DNA by size through a charged gel.

Question 32

Human genome composition

Answer 32

1.5% coding genes; rest introns, repeats, transposons, regulatory DNA.

Question 33

Retrotransposon

Answer 33

Moves via RNA intermediate (copy-paste).

Question 34

Simple transposon

Answer 34

Moves directly as DNA (cut-paste).