Biology Revision: Reproduction, Coordination, Organ Systems, and Physiology

Vocabulary flashcards covering core biological definitions and concepts across plant and animal physiology, transport, reproduction, and coordination.

Asexual reproduction

A process resulting in genetically identical offspring from one parent.

Sexual reproduction

A process involving the fusion of the nuclei of two gametes to form a zygote and producing offspring that are genetically different from each other.

Fertilisation

The fusion of the nuclei of gametes, such as a male sperm and a female egg cell.

Haploid nucleus

A nucleus containing one set of chromosomes, characteristic of gamete nuclei.

Diploid nucleus

A nucleus containing two sets of chromosomes, characteristic of a zygote nucleus.

Pollination

The transfer of pollen grains from an anther to a stigma.

Self-pollination

The transfer of pollen grains from the anther of a flower to the stigma of the same flower or a different flower on the same plant.

Cross-pollination

The transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species.

Acrosome

A structure in sperm cells containing enzymes that help the sperm penetrate the outer layers of the egg cell.

Placenta

An organ that allows the exchange of dissolved nutrients and oxygen from the mother's blood to the fetus, and carbon dioxide and excretory products from the fetus to the mother.

Umbilical cord

A structure that connects the fetus to the placenta and transports blood between them.

Amniotic fluid

A fluid inside the amniotic sac that cushions and protects the developing fetus.

Central nervous system (CNS)

The part of the mammalian nervous system consisting of the brain and spinal cord.

Peripheral nervous system (PNS)

The part of the mammalian nervous system consisting of nerves outside the brain and spinal cord.

Reflex action

An automatic and rapid response that integrates and coordinates a stimulus with the response of an effector, such as a muscle or gland.

Synapse

A junction between two neurones consisting of vesicles containing neurotransmitter molecules, a synaptic gap, and receptor proteins.

Sense organs

Groups of receptor cells that respond to specific stimuli such as light, sound, touch, temperature, and chemicals.

Accommodation

The adjustment of the eye to view near and distant objects by altering lens shape and refraction using ciliary muscles and suspensory ligaments.

Fovea

A small area of the retina containing a high concentration of cones that provides detailed vision.

Hormone

A chemical substance produced by a gland and carried by the blood that alters the activity of one or more specific target organs.

Adrenaline

A hormone secreted by adrenal glands in 'fight or flight' situations that increases breathing rate, heart rate, pupil diameter, and blood glucose concentration.

Homeostasis

The maintenance of a constant internal environment.

Negative feedback

A corrective mechanism in homeostasis where a detected change from a set point triggers responses that act to return the condition towards the set point.

Vasodilation

The widening of blood vessels that increases blood flow through skin surface capillaries to increase heat loss.

Vasoconstriction

The narrowing of blood vessels that decreases blood flow through skin surface capillaries to reduce heat loss.

Gravitropism

A plant growth response in which parts of a plant grow towards or away from gravity.

Phototropism

A plant growth response in which parts of a plant grow towards or away from the direction of a light source.

Auxin

A plant hormone made in the shoot tip that diffuses through the plant, distributes unequally in response to light and gravity, and stimulates cell elongation.

Deamination

The removal of the nitrogen-containing part of amino acids in the liver to form urea.

Pathogen

A disease-causing organism.

Transmissible disease

A disease in which the pathogen can be passed from one host to another directly or indirectly.

Active immunity

Defence against a pathogen by antibody production in the body, acquired through infection or vaccination.

Antigens

Molecules on pathogens that have specific shapes and trigger an immune response.

Antibodies

Proteins with complementary shapes that bind to specific antigens, leading to direct destruction of pathogens or marking them for phagocytosis.

Passive immunity

Short-term defence against a pathogen using antibodies acquired from another individual, such as through the placenta or breast milk, without producing memory cells.

Goblet cells

Specialised cells in the breathing system that produce mucus to trap pathogens and particles.

Aerobic respiration

Chemical reactions in cells that use oxygen to break down nutrient molecules to release energy.

Anaerobic respiration

Chemical reactions in cells that break down nutrient molecules to release energy without using oxygen, producing much less energy per glucose molecule.

Oxygen debt

The build-up of lactic acid in muscles and blood during vigorous exercise that requires extra oxygen post-exercise for aerobic respiration in the liver.

Magnification

The calculation of an enlarged appearance relative to actual size, given by $\text{Magnification} = \frac{\text{image size}}{\text{actual size}}$.

Diffusion

The net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient due to random movement.

Osmosis

The net movement of water molecules from higher to lower water potential through a partially permeable membrane.

Turgor pressure

Pressure created inside plant cells when water presses outwards against the cell wall to keep the plant supported.

Plasmolysis

The condition in plant cells placed in concentrated solutions where water is lost and the cell membrane pulls away from the cell wall.

Active transport

The movement of particles across a cell membrane from lower to higher concentration, against the concentration gradient, using protein carriers and energy from respiration.

Catalyst

A substance that increases the rate of a chemical reaction without being changed by the reaction.

Enzyme

A protein that acts as a biological catalyst in metabolic reactions.

Active site

The region of an enzyme molecule with a specific complementary shape where the substrate binds.

Denaturation

The loss of an enzyme's functional structure caused by extreme temperature or unsuitable pH, changing the active site shape so the substrate cannot fit.

Photosynthesis

The process by which plants synthesise carbohydrates from raw materials using energy from light, expressed as $6\text{CO}_2 + 6\text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$.

Chlorophyll

A green pigment found in chloroplasts that transfers energy from light into chemical energy to synthesise carbohydrates.

Limiting factor

An environmental factor in shortest supply that restricts the rate of a process such as photosynthesis from increasing further.

Ingestion

The process of taking food and drink into the body through the mouth.

Physical digestion

The breakdown of food into smaller pieces without changing the chemical structure of the food molecules to increase surface area.

Chemical digestion

The breakdown of large, insoluble molecules into small, soluble molecules that can be absorbed.

Assimilation

The uptake and use of absorbed nutrients by the cells of the body.

Egestion

The passing out of undigested food that has not been absorbed, released as faeces through the anus.

Transpiration

The loss of water vapour from leaves by evaporation at mesophyll surfaces into air spaces followed by diffusion through stomata.

Translocation

The movement of sucrose and amino acids in the phloem from regions of release (sources) to regions of use or storage (sinks).

Single circulation

A circulatory system, as in fish, where blood passes through the heart once during each complete circuit of the body.

Double circulation

A circulatory system, as in mammals, where blood passes through the heart twice per complete circuit via pulmonary and systemic pathways.

Coronary heart disease

A disease where coronary arteries become blocked, reducing the oxygen supply to the heart muscle.

Phagocytosis

The process by which phagocytes engulf and digest pathogens.

Fibrin

An insoluble protein formed from soluble fibrinogen that produces a mesh to trap blood cells and form a blood clot.

Septum of the heart

The muscular wall separating the left and right sides of the heart that prevents oxygenated and deoxygenated blood from mixing.

Left ventricle

The heart chamber with the thickest muscular wall, responsible for pumping oxygenated blood at high pressure to the entire body.

Atrioventricular valves

Valves located between the atria and ventricles that prevent backflow of blood into the atria during ventricular contraction.

Benedict's test

A food test for reducing sugars that turns from blue to brick-red upon heating.

Biuret test

A chemical test used to detect proteins that produces a purple colour in positive results.

Ethanol emulsion test

A food test for fats and oils that forms a cloudy white emulsion when the sample is dissolved and mixed with water.

Complementary base pairing in DNA

The specific pairing between bases holding the double helix together, where adenine pairs with thymine and cytosine pairs with guanine.

Aerobic respiration balanced chemical equation

$$\text{C}<em>6\text{H}</em>{12}\text{O}<em>6 + 6\text{O}</em>2 \rightarrow 6\text{CO}<em>2 + 6\text{H}</em>2\text{O}$$

Anaerobic respiration in yeast equation

$$\text{C}<em>6\text{H}</em>{12}\text{O}<em>6 \rightarrow 2\text{C}</em>2\text{H}<em>5\text{OH} + 2\text{CO}</em>2$$

Anaerobic respiration word equation in muscles

$$\text{glucose} \rightarrow \text{lactic acid}$$

Environmental conditions for seed germination

Water, oxygen, and a suitable temperature.

Adaptive features of human egg cells

Energy stores providing nutrients for early embryonic development, and a jelly coat that changes at fertilisation to prevent entry of additional sperm.

Wind-pollinated flowers

Flowers characterized by exposed, dangling anthers, large feathery stigmas, small dull petals, and large quantities of lightweight pollen.

Amylase

A digestive enzyme secreted by salivary glands and the pancreas that breaks down starch into maltose.

Maltase

A digestive enzyme located on the membranes of epithelial cells in the small intestine that breaks down maltose into glucose.

Pepsin

A protease secreted by the stomach that breaks down proteins into peptides under acidic conditions.

Trypsin

A protease secreted by the pancreas that breaks down proteins in the alkaline conditions of the small intestine.

Lipase

An enzyme secreted by the pancreas and small intestine that breaks down fats and oils into fatty acids and glycerol.

Palisade mesophyll

The upper layer of cells inside a leaf packed with numerous chloroplasts to maximise light absorption for photosynthesis.

Spongy mesophyll

The leaf tissue containing loosely packed cells with large air spaces to facilitate the diffusion of gases such as carbon dioxide and oxygen.

Cuticle

A waxy, non-cellular layer covering the leaf epidermis that prevents excessive water loss by evaporation.

Guard cells

Specialised pairs of epidermal cells that control the opening and closing of stomata to regulate gas exchange and water loss.

Root hair cells

Specialised plant epidermal cells with elongated projections that create a large surface area to absorb water and mineral ions from the soil.

Ciliated cells

Specialised cells in the respiratory tract with hair-like surface extensions that sweep mucus and trapped pathogens upwards away from the lungs.

Arteries

Thick-walled, muscular, and elastic blood vessels that transport blood away from the heart under high pressure.

Veins

Thin-walled blood vessels with wide lumens and valves that carry blood back towards the heart under low pressure.

Capillaries

Microscopic blood vessels with walls one cell thick and narrow lumens that allow the exchange of substances between blood and body tissues.

Hepatic portal vein

The blood vessel that transports nutrient-rich deoxygenated blood directly from the digestive tract to the liver.

Renal artery

The blood vessel that carries oxygenated blood carrying waste products from the aorta into the kidneys.

Blood plasma

The pale yellow liquid fraction that transports dissolved nutrients, urea, hormones, carbon dioxide, and cellular elements throughout the body.

Platelets

Small cell fragments in the circulation that are essential for the clotting mechanism to prevent blood loss and pathogen entry.

Lymphocytes

A type of white blood cell characterised by a large rounded nucleus that provides active immunity by producing specific antibodies.

Phagocytes

White blood cells with lobed or irregular nuclei that protect the body by engulfing and digesting pathogens.

Cartilage in the trachea

C-shaped rings of firm, flexible connective tissue that keep the main airway open and prevent it from collapsing during pressure changes.

Alveoli

Tiny air sacs in the lungs surrounded by capillaries, providing an extensive and thin surface for rapid gas exchange.

Intercostal muscles

Sets of antagonistic muscles situated between the ribs that contract and relax to move the ribcage during ventilation.