KS3 Biology

Cards · 50

Cell

The basic building block of all living organisms. Q: Are all organisms multicellular? A: No, some are unicellular.

Nucleus

The organelle that contains genetic material and controls cell activities. Q: Do red blood cells have one? A: No, mature ones do not.

Cytoplasm

A jelly-like substance where chemical reactions take place inside a cell. Q: What is its main component? A: Water.

Cell membrane

A flexible outer barrier controlling what enters and leaves the cell. Q: Is it fully permeable? A: No, it is selectively permeable.

Mitochondria

Structures where aerobic respiration occurs to release energy for the cell. Q: What gas do they need? A: Oxygen.

Ribosome

Tiny organelle responsible for protein synthesis in cells. Q: What key biomolecule do they make? A: Proteins.

Cell wall

A rigid outer layer made of cellulose that supports plant cells. Q: Do animal cells have one? A: No.

Chloroplast

Plant organelle containing chlorophyll where photosynthesis occurs. Q: What green pigment absorbs light here? A: Chlorophyll.

Vacuole

A large central space in plant cells filled with cell sap. Q: What does it help keep firm? A: The plant cell structure.

Tissue

A group of similar cells working together to perform a specific function. Q: Give an example in animals. A: Muscle tissue.

Organ

A structure made of different tissues working together to perform a task. Q: Is the skin an organ? A: Yes, the largest one.

Organ system

A group of organs working together to perform a major body function. Q: Which system moves blood? A: Circulatory system.

Diffusion

Net movement of particles from high to low concentration. Q: Does diffusion require cellular energy? A: No, it is passive.

Photosynthesis

Process where plants make glucose using light, carbon dioxide, and water. Q: What gas is released as a byproduct? A: Oxygen.

Chlorophyll

Green pigment in chloroplasts that absorbs light for photosynthesis. Q: Why do leaves look green? A: It reflects green light.

Stomata

Tiny pores on leaf surfaces that allow gas exchange. Q: Which cells open and close them? A: Guard cells.

Xylem

Vascular plant tissue carrying water and minerals up from roots. Q: Does xylem flow upwards, downwards, or both? A: Upwards only.

Phloem

Plant tissue transporting sugars and nutrients throughout the plant. Q: What sugar is commonly transported? A: Sucrose.

Transpiration

The evaporation of water from a plant's leaves. Q: Does warm, dry weather increase or decrease it? A: Increases it.

Aerobic respiration

Releasing energy from glucose using oxygen, producing water and CO2. Q: Where in the cell does it mostly happen? A: Mitochondria.

Anaerobic respiration

Releasing energy from glucose without oxygen, producing lactic acid. Q: Does it produce more or less energy than aerobic? A: Less.

Fermentation

Anaerobic respiration in yeast producing ethanol and carbon dioxide. Q: Name a food made using yeast fermentation. A: Bread.

Enzyme

A biological catalyst that speeds up chemical reactions without being used up. Q: What are enzymes made of? A: Proteins.

Active site

The specific region of an enzyme where the substrate binds. Q: What happens if it changes shape? A: The enzyme denatures.

Denaturation

Permanent change in an enzyme's shape caused by extreme heat or pH. Q: Can a denatured enzyme function? A: No.

Peristalsis

Wave-like muscle contractions moving food through the digestive tract. Q: Which tube connects throat to stomach? A: Oesophagus.

Amylase

An enzyme that breaks down starch into simple sugars. Q: Where is it first secreted in humans? A: The salivary glands.

Villi

Finger-like projections in the small intestine increasing absorption area. Q: How does their shape help? A: It increases surface area.

Alveoli

Tiny air sacs in the lungs where gas exchange takes place. Q: Which gas moves into the blood here? A: Oxygen.

Red blood cell

Blood cell containing haemoglobin to transport oxygen around the body. Q: Why do they lack a nucleus? A: To carry more haemoglobin.

White blood cell

Immune system cell that defends against pathogens and infections. Q: What do some produce to tag pathogens? A: Antibodies.

Artery

Thick-walled blood vessel carrying blood away from the heart under high pressure. Q: Do most carry oxygenated blood? A: Yes.

Vein

Blood vessel carrying blood back to the heart, containing valves. Q: Why do veins have valves? A: To prevent backflow of blood.

Capillary

Microscopic blood vessel with walls one cell thick for efficient exchange. Q: Why are walls thin? A: To shorten diffusion distance.

Pathogen

A microorganism that causes disease, such as bacteria or viruses. Q: Are all bacteria pathogens? A: No, many are harmless or useful.

Gamete

A specialized sex cell with half the normal number of chromosomes. Q: Name the human female gamete. A: Ovum or egg cell.

Fertilisation

The fusion of the male and female gamete nuclei to form a zygote. Q: Where does this usually happen in humans? A: Oviduct or fallopian tube.

Pollination

Transfer of pollen from the male anther to the female stigma of a flower. Q: Name one animal pollinator. A: Bee.

Ecosystem

A community of living organisms interacting with their physical environment. Q: Does it include non-living factors? A: Yes.

Producer

An organism that produces its own food, usually through photosynthesis. Q: Give an example. A: Green plants or algae.

Herbivore

An animal that feeds exclusively or primarily on plants. Q: What level consumer are they in a food chain? A: Primary consumer.

Carnivore

An animal that gets food from killing and eating other animals. Q: Are lions herbivores or carnivores? A: Carnivores.

Decomposer

An organism like fungi or bacteria that breaks down dead organic matter. Q: What do they return to the soil? A: Nutrients.

Bioaccumulation

The build-up of toxins in an organism over time along a food chain. Q: Which trophic level receives the highest concentration? A: Top predators.

Biodiversity

The variety of all different species of organisms in an ecosystem. Q: Does high biodiversity make ecosystems more stable? A: Yes.

Chromosome

A thread-like structure of DNA carrying genes inside the nucleus. Q: How many pairs do normal human cells have? A: 23 pairs.

Gene

A short section of DNA that codes for a specific characteristic or protein. Q: Where are genes located? A: On chromosomes.

Variation

Differences in characteristics between individuals of the same species. Q: Name an inherited variation in humans. A: Natural eye colour.

Natural selection

Process where organisms better adapted to their environment survive and reproduce. Q: Who proposed this theory? A: Charles Darwin.

Extinction

The permanent loss of all individuals of a particular species worldwide. Q: Name an extinct bird species. A: Dodo.