BIOLOGY PAPER 1:

What is a eukaryotic cell?

A cell with a nucleus and membrane-bound organelles, found in animals, plants, fungi, and protists.

What is a prokaryotic cell?

A simpler cell without a nucleus, such as bacteria. DNA is free in the cytoplasm.

What is the function of the nucleus?

It contains genetic material and controls cell activities.

What is the function of mitochondria?

Site of aerobic respiration, releasing energy for the cell.

What is the function of ribosomes?

They are the site of protein synthesis.

What is the function of the cell membrane?

It controls the movement of substances in and out of the cell.

What is the function of the cell wall?

Provides structure and support; made of cellulose in plants.

What is the function of the vacuole?

Contains cell sap and maintains internal pressure in plant cells.

What is the function of chloroplasts?

Site of photosynthesis; contains chlorophyll to absorb light.

What are plasmids?

Small loops of DNA found in bacterial cells.

What is the difference between light and electron microscopes?

Light microscopes have lower resolution (~1000x); electron microscopes offer much higher resolution and magnification (~500,000x).

What is magnification and how is it calculated?

Magnification = Image size ÷ Actual size.

What is resolution in microscopy?

The ability to distinguish two close objects as separate.

Describe binary fission.

Bacterial cell division where the cell splits into two genetically identical cells.

What is mitosis used for?

Growth, repair, and asexual reproduction.

Describe the stages of the cell cycle.

Interphase (growth and DNA replication), Mitosis (nucleus divides), Cytokinesis (cell divides).

What are stem cells?

Undifferentiated cells that can develop into different cell types.

What are embryonic stem cells?

Stem cells from early embryos that can differentiate into any cell type.

What are adult stem cells?

Found in bone marrow; can form certain cells like red/white blood cells and platelets.

What is therapeutic cloning?

Creating an embryo with the same DNA as a patient to produce matching stem cells for treatment.

What are ethical concerns about embryonic stem cells?

Destroying embryos to obtain stem cells raises moral and ethical questions about the start of life.

What is diffusion?

Movement of particles from high to low concentration.

Give an example of diffusion in the body.

Oxygen diffusing from alveoli into the blood in the lungs.

What is osmosis?

Diffusion of water across a partially permeable membrane from high water concentration to low.

What is active transport?

Movement of substances against a concentration gradient, requiring energy from respiration.

Where does active transport occur in plants?

In root hair cells to absorb mineral ions from the soil.

Where does active transport occur in animals?

In the small intestine to absorb glucose from the gut into the blood.

What is a concentration gradient?

The difference in concentration between two regions.

What is a partially permeable membrane?

A membrane that only allows some molecules (like water) to pass through.

How do surface area and volume affect diffusion?

Larger surface area to volume ratio increases the rate of diffusion.

What adaptations do alveoli have for gas exchange?

Large surface area, thin walls, moist lining, and good blood supply.

What are the adaptations of root hair cells?

Long extensions increase surface area to absorb water and mineral ions.

What are the adaptations of sperm cells?

Tail for movement, many mitochondria for energy, enzymes to digest egg membrane.

What are the adaptations of nerve cells?

Long axon for transmitting signals, branched endings (dendrites) to connect with other cells.

What are the adaptations of muscle cells?

Long cells that can contract, lots of mitochondria to release energy.

What are the adaptations of xylem cells?

Hollow and strengthened with lignin to carry water and mineral ions in one direction.

What are the adaptations of phloem cells?

Sieve plates and companion cells allow movement of sugars throughout the plant.

What is a tissue?

A group of similar cells working together to perform a specific function.

What is an organ?

A group of different tissues working together to perform a specific function.

What is an organ system?

A group of organs that work together to carry out a particular life process.

Give an example of an organ system.

The digestive system – breaks down food and absorbs nutrients.

Why is cell differentiation important?

It allows cells to specialise and carry out specific functions effectively.

When do most animal cells differentiate?

At an early stage in embryonic development.

Can plant cells differentiate throughout life?

Yes, many plant cells can continue to differentiate when needed.

What is a specialised cell?

A cell that has adapted structures to perform a specific job.

Give an example of a specialised plant cell.

Palisade cells – full of chloroplasts to maximise photosynthesis.

What is the function of ciliated epithelial cells?

Move mucus and trapped particles up and out of the airways.

What is the function of red blood cells?

Carry oxygen using haemoglobin; have no nucleus to maximise space.

Why don’t red blood cells have a nucleus?

To make room for more haemoglobin, increasing oxygen-carrying capacity.

What is haemoglobin?

A red protein in red blood cells that binds with oxygen to transport it.

What is the function of the digestive system?

To break down large, insoluble food molecules into smaller, soluble ones that can be absorbed into the blood.

What are the main parts of the digestive system?

Mouth, oesophagus, stomach, small intestine, large intestine, liver, pancreas.

What is the role of the mouth in digestion?

Mechanical digestion (chewing) and chemical digestion of starch by amylase.

What is the function of the stomach?

Produces hydrochloric acid to kill bacteria and protease (pepsin) to digest proteins.

What is the function of the liver in digestion?

Produces bile to neutralise stomach acid and emulsify fats.

What is the function of the gall bladder?

Stores and releases bile into the small intestine.

What is the function of the pancreas?

Produces digestive enzymes: amylase, protease, and lipase.

What is the function of the small intestine?

Digests and absorbs nutrients using villi for a large surface area.

What is the function of the large intestine?

Absorbs water from undigested food to form faeces.

What is the function of enzymes in digestion?

Break large, insoluble molecules into small, soluble ones.

What is the substrate and product of amylase?

Starch → sugars (mainly maltose).

Where is amylase produced?

Salivary glands, pancreas, and small intestine.

What is the substrate and product of protease?

Proteins → amino acids.

Where is protease produced?

Stomach (pepsin), pancreas, and small intestine.

What is the substrate and product of lipase?

Lipids → fatty acids + glycerol.

Where is lipase produced?

Pancreas and small intestine.

What is bile and what does it do?

An alkaline substance that emulsifies fats and neutralises stomach acid.

What is emulsification?

Breaking down large fat droplets into smaller ones to increase surface area for lipase action.

What are villi and what is their function?

Finger-like projections in the small intestine that absorb nutrients.

How are villi adapted for absorption?

Large surface area, thin walls, good blood supply.

What is the function of the heart?

To pump blood around the body via the circulatory system.

What type of circulatory system do humans have?

Double circulatory system (pulmonary and systemic circuits).

What is the function of the right side of the heart?

Pumps deoxygenated blood to the lungs.

What is the function of the left side of the heart?

Pumps oxygenated blood to the body.

Why does the left side of the heart have a thicker wall?

It pumps blood at higher pressure to the entire body.

What is the function of arteries?

Carry blood away from the heart under high pressure.

What is the function of veins?

Carry blood to the heart under lower pressure; contain valves.

What is the function of capillaries?

Exchange substances (e.g. oxygen, nutrients) between blood and tissues.

What are the features of red blood cells?

No nucleus, biconcave shape, contains haemoglobin to carry oxygen.

What are the types of white blood cells?

Phagocytes (engulf pathogens) and lymphocytes (produce antibodies).

What is the function of platelets?

Cell fragments that help blood clot at wounds.

What is the function of plasma?

Liquid component that carries blood cells, hormones, nutrients, CO₂, and urea.

What is coronary heart disease?

Fatty material builds up in coronary arteries, reducing blood flow to the heart muscle.

What are stents and how do they work?

Metal mesh tubes inserted into arteries to keep them open.

What are statins and what do they do?

Drugs that reduce blood cholesterol and slow down fatty deposit formation.

What is a faulty heart valve and how can it be treated?

A valve that doesn’t open/close properly; treated with biological or mechanical valves.

What is a pacemaker?

An electrical device implanted under the skin to regulate heart rhythm.

What is artificial blood used for?

Temporary replacement to carry oxygen after severe blood loss.

What are artificial hearts used for?

Short-term replacement for patients waiting for a heart transplant.

What is a non-communicable disease?

A disease that cannot be spread between people (e.g. cancer, CHD).

What lifestyle factors affect non-communicable diseases?

Smoking, alcohol, diet, lack of exercise.

How does smoking affect health?

Can lead to lung cancer, heart disease, and damages blood vessels.

How does alcohol affect health?

Causes liver damage, brain damage, and affects reaction time.

How does obesity affect health?

Increases risk of type 2 diabetes, high blood pressure, and CHD.

What is a risk factor?

Anything that increases the chance of developing a disease.

What is cancer?

Uncontrolled cell division that forms a tumour.

What is a benign tumour?

A non-cancerous growth that doesn’t spread.

What is a malignant tumour?

A cancerous tumour that spreads to other parts of the body.

How can cancer be treated?

Surgery, radiotherapy, chemotherapy.

What are the main plant organs?

Roots, stems, and leaves – work together for transport and photosynthesis.