Biology Y10 Definitions

Definitions for the examination on year 10 Biology

Diffusion

Movement of particles from high to low concentration.

Osmosis

Movement of water across a semi-permeable membrane.

Active Transport

Movement of substances against the concentration gradient using energy.

DNA

Deoxyribonucleic Acid, a long molecule carrying genetic information, in an irregular double helix structure.

Gene

Section of DNA controlling a certain trait.

Chromosome

Structure containing DNA in the nucleus. Humans have 46 chromosomes, arranged in to 23 pairs of chromatids, and one chromosome is passed on to offspring in fertilization.

Inheritance

Passing of traits from parents to offspring.

Photosynthesis

Process plantss use to make glucose from sunlight, water, and carbon dioxide as nutrients.

Chlorophyll

Green pigment that absorbs light energy inside plants.

Glucose

Sugar produced during photosynthesis, used as nutrients and energy for plants.

Stomata

Small pores on leaves used for gas exchange.

Ecosystem

Organisms interacting with their environment around them.

Biodiversity

Variety of living organisms (animals and plants) in an area.

Habitat

The natural place in which an organism lives and can find the necessary factors to survive.

Adaptation

Feature that helps an organism survive in its ecosystem.

Producer

Organism that makes its own food (algae)

Consumer

Organism that eats other organisms to survive (sharks)

Food Chain

Sequence showing energy transfer between organisms (e.g. Grass → Grasshopper → Frog)

Food Web

Multiple interconnected food chains

Chargaff’s Rule

In DNA, the nitrogenous base Adenine pairs with Thymine and Cytosine pairs with Guanine, and both have equal amounts of A-T and C-G.

Lindemann’s Rule

Only 10% of an organism’s energy is transferred from one trophic level to the next in a food chain.

Cell Theory

The theory that explains cells as the basic units of all life.

4 Tenets of Natural Selection

Competition (because resources are limited, individuals must compete for them)

Heritable Variation (individuals in a population show differences in their traits, as beneficial traits are heritable, so they become more common over generations)

Overproduction of Offspring (more of offspring are produced than the environment can support)

Survival of the Fittest (individuals with traits that give them an advantage in their environment are more likely to survive and reproduce)

Natural Selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring.

Lock and Key Theory

An enzyme’s active site has a fixed, complementary shape that fits only a specific substrate - much like a key fits a particular lock - explaining enzyme specificity.