Revision Biology for IGCSE

Comprehensive vocabulary flashcards covering the IGCSE Biology syllabus including cell biology, plant physiology, ecology, human anatomy, homeostasis, genetics, and infectious diseases.

Nucleus

Contains genetic material, which controls the activities of the cell.

Cytoplasm

The area where most chemical processes take place, controlled by enzymes.

Cell membrane

Controls the movement of substances into and out of the cell.

Mitochondria

The site where most energy is released by respiration.

Ribosomes

The site where protein synthesis happens.

Cell wall

A plant cell part that strengthens the cell.

Chloroplasts

Contain chlorophyll, which absorbs light energy for photosynthesis.

Permanent vacuole

Part of a plant cell filled with cell sap to help keep the cell turgid.

Leaf cell

A cell packed with chloroplasts and regular shaped to absorb light energy efficiently for photosynthesis.

Root hair cell

Absorbs water and mineral ions from the soil through a long 'finger-like' process with a thin wall for a large surface area.

Sperm cell

A specialized cell for fertilizing an egg; contains genetic information, an enzyme in the head, and mitochondria for energy in the middle section.

Red blood cells

Cells containing haemoglobin to carry oxygen with no nucleus to maximize space.

Diffusion

The movement of particles from a region of high concentration to a region of low concentration down a concentration gradient.

Osmosis

The movement of water from a less concentrated solution to a more concentrated solution through a partially permeable membrane.

Photosynthesis

The chemical change in green plants where light energy is used to react carbon dioxide with water to produce glucose and oxygen.

Equation for Photosynthesis

$$Carbon dioxide + water \xrightarrow{light \, energy} glucose + oxygen$$

Nitrate

A mineral ion needed by plants for making amino acids and proteins; deficiency causes stunted growth.

Magnesium

A mineral ion needed for making chlorophyll; deficiency causes leaves to turn yellow.

Producers

Green plants that make food by photosynthesis.

Primary consumers

Herbivores that eat plant material, such as rabbits or cows.

Secondary consumers

Carnivores that eat animal material, such as lions or cats.

Decomposers

Organisms that feed on dead and decaying matter and undigested plant and animal matter in faeces.

Biomass

The mass of living material at a stage in a food chain.

Carbon cycle

The process showing how carbon moves from the atmosphere into living things and back again as carbon dioxide.

Enzymes

Biological catalysts made of proteins that increase the rate of chemical reactions without being used up.

Active site

The place on an enzyme where substrate molecules fit for a reaction to occur.

Denatured

When the shape of an enzyme changes due to high temperature or extreme pH so that the active site no longer works.

Aerobic respiration

A chemical process in mitochondria where energy is released from food: $Glucose + oxygen \rightarrow carbon \, dioxide + water (+energy)$

Amylase

A carbohydrase produced in the salivary glands, pancreas, and small intestine that breaks starch into sugars.

Protease

An enzyme produced in the stomach, pancreas, and small intestine that breaks proteins into amino acids.

Lipase

An enzyme produced in the pancreas and small intestine that breaks lipids into fatty acids and glycerol.

Bile

A substance that neutralises stomach acid to provide the alkaline conditions needed in the small intestine.

Homeostasis

The maintenance of conditions inside the body within narrow limits, including water content, ion content, and body temperature.

Insulin

A hormone produced by the pancreas that reduces blood glucose levels by moving glucose into cells.

Type 1 Diabetes

A disease where the pancreas does not produce enough insulin, leading to high glucose levels.

Urea

A waste product produced in the liver when excess amino acids are broken down, removed by the kidneys as urine.

Thermoregulatory centre

The part of the brain that monitors and controls body temperature using nerve impulses from receptors in the brain and skin.

Hormones

Chemical substances secreted by glands that travel in the bloodstream to regulate processes in target organs.

Adrenalin

A hormone from the adrenal gland that prepares the body for 'fight or flight' action.

FSH (Follicle stimulating hormone)

A pituitary hormone that causes an egg to mature in an ovary and stimulates oestrogen production.

LH (Luteinising hormone)

A hormone that triggers the release of a mature egg from the ovary.

Central nervous system (CNS)

Consists of the brain and spinal cord in humans.

Receptors

Groups of specialised cells in sense organs that detect stimuli and turn them into electrical impulses.

Effectors

Parts of the body, such as muscles or glands, that produce a response to a stimulus.

Synapse

A tiny gap between two neurones where signals cross using chemicals.

Reflex action

A rapid, automatic response to a stimulus that does not involve the brain.

Pathogens

Microorganisms like bacteria and viruses that cause infectious disease.

Phagocytes

White blood cells that ingest and absorb pathogens or toxins to destroy them.

Lymphocytes

White blood cells that produce specific antibodies or antitoxins to neutralise pathogens and toxins.

Antigens

Foreign chemicals on pathogens that stimulate an immune response.

Vaccination

The introduction of inactive or dead pathogens into the body to stimulate white blood cells to produce antibodies.

Antibiotics

Substances like penicillin that kill bacteria or stop their growth but do not work against viruses.

Metabolic rate

The speed at which chemical reactions take place in the body, which increases during exercise.

LDL (Low-density lipoproteins)

Often called 'bad' cholesterol; they carry cholesterol from the liver to cells and can cause fat buildup in arteries.

HDL (High-density lipoproteins)

Often called 'good' cholesterol; they carry excess cholesterol back to the liver.

Adaptation

Specific features or characteristics that allow an organism to live successfully in its habitat.

Genetic engineering

The transfer of genetic information from one species to another to produce a unique set of genes.

Selective breeding

A process where humans choose individuals with desired features to reproduce, also called artificial selection.

Kingdoms

The first rank of classification consisting of five groups: animals, plants, fungi, prokaryotes, and protoctists.

Arteries

Blood vessels with thick outer walls and muscle layers that carry blood away from the heart under high pressure.

Veins

Blood vessels with thin walls and one-way valves that return blood to the heart under low pressure.

Coronary arteries

The blood vessels that supply oxygen and nutrients directly to the heart muscle cells.

Nitrogen fixation

The process of changing unreactive nitrogen gas into reactive forms like nitrates, occurring via lightning, the Haber Process, or bacteria.