Honor's Biology Semester 2 Review

A comprehensive practice exam review covering cellular respiration, cell division, genetics, and molecular biology (DNA/RNA).

What is the general process of cellular respiration?

Respiration is the process in which food (glucose) is converted to energy ($ATP$).

What are the four steps of cellular respiration?

1. Glycolysis, 2. The Bridge Reaction, 3. Kreb's Cycle, and 4. The Electron Transport Chain.

Where does glycolysis occur and is it aerobic or anaerobic?

Glycolysis occurs in the cytoplasm and is anaerobic (does not require oxygen).

Why does glycolysis result in a net gain of only $2$ ATP if $4$ ATP are actually produced?

$2$ ATP molecules are used up to make the reaction start, resulting in a net gain of $2$ ($4 - 2 = 2$).

In cellular respiration, what is the 'Bridge Reaction'?

The second stage where pyruvic acid (a $3$-carbon compound) is converted into Acetyl CoA (a $2$-carbon compound) by the removal of $CO_2$.

What electron carriers are produced during the first three stages of respiration to be used in the electron transport chain?

$NADH$ and $FADH_2$.

How do photosynthesis and cellular respiration relate to each other?

They are opposites; the products of photosynthesis are the reactants of cellular respiration, and the products of cellular respiration are the reactants of photosynthesis.

What is the equation for cellular respiration?

$$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$$

What enzyme is responsible for converting ADP to ATP as hydrogen protons flow through it during the final stage of respiration?

ATP synthase.

What happens to the surface area to volume ratio as a cell grows larger?

The surface area to volume ratio decreases.

What are the three parts of the cell cycle collectively known as interphase?

$G_1$, $S$, and $G_2$ phase.

During which phase of the cell cycle is DNA replicated?

The $S$ phase.

What are the four phases of mitosis?

Prophase, Metaphase, Anaphase, and Telophase.

How does cytokinesis differ between plant and animal cells?

In animal cells, the cell membrane pinches in; in plant cells, a cell plate forms between the two chromatin masses.

What is the difference between diploid ($2N$) and haploid ($1N$) cells?

Diploid cells contain two sets of chromosomes, while haploid cells contain only one set.

If an organism has a haploid number of $1N = 16$, how many chromosomes are in its body cells?

$32$ chromosomes ($2N$).

What is the purpose of meiosis?

To produce haploid gametes (sex cells) such as sperm and egg.

What is 'crossing over' in meiosis?

The exchange of genetic information between segments of homologous chromosomes during Prophase I.

What is Mendel's Law of Segregation?

Every individual has two alleles for a trait which separate during the formation of the sex cells.

What is the difference between homozygous and heterozygous?

Homozygous means an organism has two of the same allele for a trait; heterozygous means it has two different alleles.

Contrast incomplete dominance and codominance.

Incomplete dominance results in a blending of phenotypes (e.g., pink flowers from red and white parents). Codominance results in both alleles being expressed simultaneously.

Why does colorblindness occur more often in males than in females?

Because colorblindness is a sex-linked trait located on the $X$ chromosome, and males only have one $X$, making them more susceptible.

What are the four possible blood types in humans?

Type A, Type B, Type AB, and Type O.

Define the chromosome mutation 'Nondisjunction'.

When homologous chromosomes do not separate during meiosis I or sister chromatids fail to separate during meiosis II.

What are the three parts of a DNA nucleotide?

A sugar (deoxyribose), a phosphate group, and a nitrogen base.

Which nitrogen bases pair together in DNA according to Chargaff's rules?

Adenine pairs with Thymine, and Cytosine pairs with Guanine.

What enzymes are responsible for unzipping the DNA double helix and assembling new chains during replication?

Helicase unzips the helix, and DNA Polymerase assembles the new chains.

List three differences between DNA and RNA.

1. DNA has deoxyribose, RNA has ribose. 2. DNA is double-stranded, RNA is single-stranded. 3. DNA has Thymine, RNA has Uracil.

What is transcription?

The process of making a strand of mRNA from a strand of DNA.

What is a codon?

A group of $3$ nitrogen bases that form the code for one particular amino acid.