IB DP Biology SL Basic Knowledge Questions

Flashcards created for IBDP Biology 2025 Basic Knowledge Questions for review and study purposes.

What are the four properties of water that are useful for life?

1. Excellent solvent 2. Transparent to light 3. High specific heat capacity 4. Ice is less dense than water

What is cohesion in terms of water?

Water molecules are attracted to each other.

Define adhesion as it pertains to water.

Water molecules are attracted to other polar or charged molecules.

What are hydrophilic substances?

Substances that can dissolve in water, usually polar or charged. Examples include glucose, amino acids, and ions.

Define hydrophobic substances.

Substances that cannot dissolve in water, generally non-polar. Examples include fats and steroids.

What is the general relationship between hydrogen bonds and boiling point?

More hydrogen bonds increase the boiling point because more energy (heat) is required to separate the molecules.

What is the implication of a substance's polarity on its ability to dissolve in water?

The more charges or polarity a molecule has, the better it dissolves in water.

List the three components of a nucleotide.

Nitrogenous base, pentose sugar, phosphate group.

State the differences between DNA and RNA.

1. RNA is single-stranded while DNA is double-stranded. 2. RNA uses uracil while DNA uses thymine. 3. RNA nucleotides have ribose; DNA has deoxyribose.

What does complementary base pairing allow in DNA?

It enables accurate replication of DNA.

What is Chargaff's rule?

%A = %T and %G = %C.

What is the principal function of the fluid mosaic model in cellular membranes?

To illustrate the dynamic and flexible nature of cell membranes with proteins and lipids freely moving within the phospholipid bilayer.

How do mutations affect genetic information?

Mutations can change the sequence of DNA, which can alter the amino acid sequence of proteins and thus their function.

What is the significance of the Hardy-Weinberg equilibrium?

It provides a model to study allele frequencies in populations that are not evolving.

Define phenotypic plasticity.

The ability of an organism to adjust its phenotype in response to changes in its environment.

What is the role of auxin in plant growth?

Auxin promotes cell elongation in the direction of light, allowing plants to grow towards light sources.

State the difference between primary and secondary succession.

Primary succession occurs on bare substrates without soil development; secondary succession occurs in areas where soil already exists after a disturbance.

What is apoptosis?

Programmed cell death—a process to remove cells that are damaged, unnecessary, or potentially harmful.

What is the role of histones in DNA organization?

Histones help package DNA into structural units called nucleosomes, which condense to form chromosomes.

Define biomagnification.

The increasing concentration of toxins in the tissues of organisms at successively higher levels in a food chain.

What factors affect the water potential of a plant cell?

Water potential is affected by solute concentration (Ψs) and pressure potential (Ψp).