Biology Basics Quiz

Archaea, E. coli, and bacteria do not have a nucleus.

DNA similarities reveal evolutionary connections between organisms.

A theory is broader, supported by evidence; a hypothesis is a testable, specific prediction.

The variable manipulated in a scientific experiment.

Critical thinking reduces errors and biases in science by encouraging different perspectives.

Atomic number plus the number of neutrons equals the atomic weight (mass).

Covalent bonds share electrons; ionic bonds transfer electrons.

A carbon atom can form a maximum of four covalent bonds.

The cell membrane is a flexible structure composed of a phospholipid bilayer with embedded proteins, carbohydrates, and cholesterol.

A negative change in Gibbs free energy indicates that a reaction releases energy and is spontaneous (favored) under the given conditions.

Humans lack the enzyme cellulase, preventing them from digesting cellulose, a major component of plant cell walls.

A peptide bond links amino acids together, forming the backbone of proteins.

RNA is primarily responsible for protein synthesis, translating genetic information from DNA into functional proteins.

During centrifugation, denser components pellet out first: nucleus, then mitochondria, then ribosomes.

Ribosomes are the sites of protein synthesis, responsible for assembling amino acids into polypeptide chains.

The smooth endoplasmic reticulum (ER) primarily detoxifies drugs and other harmful substances within cells.

The central vacuole occupies the largest volume in plant cells, playing a vital role in storage, support, and turgor pressure.

Plant cell walls are primarily composed of cellulose, a complex carbohydrate that provides structural support.

DNA replication produces two new DNA molecules, each containing one original (old) strand and one newly synthesized strand.

After three cycles of DNA replication, 75% of the DNA strands are 'light' (containing only the lighter nitrogen isotope).

When a stop codon is encountered during translation, the ribosome halts protein synthesis and releases the completed protein.

A polysome is a cluster of ribosomes translating the same mRNA molecule, allowing for the efficient synthesis of multiple copies of the same protein.

The lysogenic cycle allows viral DNA to integrate into the host's genome, becoming a part of the host's DNA.

Retroviruses like HIV integrate their RNA into the host's genome by reverse transcribing it into DNA, using the enzyme reverse transcriptase.

Vaccines introduce weakened or inactive pathogens to the immune system, triggering an immune response without causing the full disease.

Reverse transcriptase is an enzyme that converts RNA into DNA.

Watson and Crick used X-ray crystallography data from Rosalind Franklin to deduce the double helix structure of DNA.

If adenine (A) makes up 20% of the bases in DNA, then cytosine (C) also makes up 20%, because A always pairs with T and C with G.

DNA polymerase III is the enzyme responsible for elongating DNA strands during replication.

A human gamete (sperm or egg cell) contains 23 chromosomes, half the number of chromosomes in a normal human cell.

A cross between AaBB and aabb individuals can result in two different phenotypes, as the dominant allele 'A' will always express itself.

When a homozygous dominant individual (AA) is crossed with a heterozygous individual (Aa), 50% of the offspring will be homozygous dominant (AA).

A sex-linked recessive trait is carried on the X chromosome, and females have a 50% chance of inheriting the trait from a color-blind father.

The complementary DNA strand is the opposite sequence of a given strand, with A pairing with T, and C pairing with G.

If thymine makes up 15% of a DNA sample, then guanine will make up 35% because A and T, and C and G pair up in equal amounts.

Mitosis is used in cloning to create genetically identical copies of an organism, ensuring that the offspring has the same DNA as the parent.

A reciprocal cross involves switching the phenotypes of the parents to determine if a trait is sex-linked. For example, a female with yellow-body crossed with a male with red-body, then a female with red-body crossed with a male with yellow-body.