biology paper 1

Cells can be prokaryotic or eukaryotic. What is the difference?

Prokaryotic cells have no nucleus and no membrane-bound organelles. Eukaryotic cells have a nucleus and organelles.

Name three structures found in bacterial cells.

Cell membrane, cytoplasm, circular DNA.

What are plasmids?

Small rings of DNA found in bacterial cells.

What is the function of the nucleus?

Contains genetic material and controls cell activities.

What is the function of the cell membrane?

Controls movement of substances in and out of the cell.

What is the function of cytoplasm?

Site of chemical reactions.

What is the function of mitochondria?

Site of aerobic respiration and energy release.

What is the function of ribosomes?

Site of protein synthesis.

What structures are found in plant cells but not animal cells?

Cell wall, chloroplasts and permanent vacuole.

What is the function of the cell wall?

Strengthens and supports the cell.

What is the function of chloroplasts?

Site of photosynthesis.

What is the function of the permanent vacuole?

Contains cell sap and helps maintain cell pressure.

What is diffusion?

The net movement of particles from high concentration to low concentration.

What is osmosis?

The net movement of water molecules through a partially permeable membrane from high water concentration to low water concentration.

What is active transport?

Movement of substances from low concentration to high concentration using energy.

What are the three stages of the cell cycle?

Growth, DNA replication and mitosis.

What is mitosis?

Cell division producing two genetically identical daughter cells.

What are stem cells?

Undifferentiated cells that can become different specialised cells.

What is a specialised cell?

A cell adapted to carry out a specific function.

Name a feature of a sperm cell.

Tail for swimming and many mitochondria for energy.

Name a feature of a nerve cell.

Long axon to carry electrical impulses.

Name a feature of a muscle cell.

Contains many mitochondria for respiration.

What is an organ?

A group of tissues working together to perform a function.

What is a tissue?

A group of similar cells working together.

What is an organ system?

A group of organs working together.

What enzyme breaks down starch?

Amylase.

What enzyme breaks down proteins?

Protease.

What enzyme breaks down lipids?

Lipase.

Where is amylase produced?

Salivary glands, pancreas and small intestine.

Where are proteases produced?

Stomach, pancreas and small intestine.

Where are lipases produced?

Pancreas and small intestine.

What is the role of bile?

Neutralises stomach acid and emulsifies fats.

What does emulsification do?

Breaks fats into small droplets, increasing surface area.

What is the lock and key theory?

Only a substrate with the correct shape fits into an enzyme’s active site.

What is the optimum temperature for human enzymes?

About 37°C.

What happens to enzymes at high temperatures?

They denature and change shape.

What does Benedict’s test test for?

Reducing sugars.

What colour change shows a positive Benedict’s test?

Blue to brick red.

What does iodine solution test for?

Starch.

What colour change shows a positive iodine test?

Brown/orange to blue-black.

What does Biuret test test for?

Proteins.

What colour change shows a positive Biuret test?

Blue to purple/lilac.

What does the ethanol emulsion test test for?

Lipids.

What result shows a positive lipid test?

Cloudy white emulsion.

What are the four components of blood?

Plasma, red blood cells, white blood cells and platelets.

What is the function of plasma?

Transports dissolved substances around the body.

What is the function of red blood cells?

Transport oxygen.

What pigment is found in red blood cells?

Haemoglobin.

Why are red blood cells efficient at carrying oxygen?

Large surface area, biconcave shape and no nucleus.

What is the function of white blood cells?

Defend against pathogens.

How do white blood cells defend the body?

Phagocytosis, producing antibodies and producing antitoxins.

What is the function of platelets?

Help blood clot.

What are coronary arteries?

Arteries supplying the heart muscle with oxygenated blood.

What causes coronary heart disease?

Fatty deposits narrowing coronary arteries.

What is a stent?

A mesh tube used to keep arteries open.

What is a statin?

A drug that lowers blood cholesterol.

What is a biological valve replacement?

A valve from a human or animal donor.

What is a mechanical valve replacement?

A man-made valve.

What are the advantages of mechanical valves?

Last a long time.

What is the disadvantage of mechanical valves?

Require lifelong blood-thinning medication.

What is cancer?

Uncontrolled cell division.

What is a benign tumour?

A tumour contained in one place that does not spread.

What is a malignant tumour?

A tumour that invades tissues and spreads.

Name two lifestyle factors that increase cancer risk.

Smoking and UV exposure.

What is a pathogen?

A microorganism that causes disease.

Name the four types of pathogen.

Bacteria, viruses, fungi and protists.

How do bacteria make us ill?

Producing toxins and damaging cells.

How do viruses make us ill?

Entering cells and reproducing inside them.

What disease is caused by Salmonella bacteria?

Food poisoning.

How can Salmonella infection be prevented?

Cooking food thoroughly and good hygiene.

What disease is caused by Gonorrhoea?

A sexually transmitted bacterial infection.

How can Gonorrhoea be prevented?

Using condoms.

What disease is caused by the tobacco mosaic virus?

Tobacco mosaic disease.

What effect does tobacco mosaic virus have on plants?

Reduces photosynthesis and growth.

What disease is caused by Rose Black Spot?

Rose black spot disease.

How can Rose Black Spot be controlled?

Fungicides and removing infected leaves.

What disease is caused by Plasmodium?

Malaria.

How is malaria spread?

By mosquitoes.

What is the first line of defence against pathogens?

Skin and blood clotting.

How does mucus help defend the body?

Traps pathogens.

How do cilia help defend the body?

Move mucus and trapped pathogens out of airways.

What is phagocytosis?

White blood cells engulfing and digesting pathogens.

What are antibodies?

Proteins that bind to specific antigens on pathogens.

What are antitoxins?

Chemicals that neutralise toxins produced by pathogens.

How do vaccines work?

Stimulate white blood cells to produce antibodies and memory cells.

What are antibiotics?

Medicines that kill bacteria.

Why do antibiotics not work on viruses?

Viruses reproduce inside cells, making them difficult to target.

What is antibiotic resistance?

When bacteria evolve so antibiotics no longer kill them.

How can antibiotic resistance be reduced?

Only use antibiotics when necessary and complete the full course.

What is photosynthesis?

The process by which plants make glucose using light energy.

Word equation for photosynthesis.

Carbon dioxide + water → glucose + oxygen.

Balanced symbol equation for photosynthesis.

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.

Where does photosynthesis take place?

In chloroplasts.

What are the limiting factors of photosynthesis?

Light intensity, carbon dioxide concentration, temperature and chlorophyll.

How does increasing light intensity affect photosynthesis?

Increases rate until another factor becomes limiting.

How does increasing carbon dioxide concentration affect photosynthesis?

Increases rate until another factor becomes limiting.

How does temperature affect photosynthesis?

Increases rate to an optimum, then enzymes denature and rate falls.

What is glucose used for in plants?

Respiration, making cellulose, making proteins, making fats and storage as starch.

What is aerobic respiration?

Respiration using oxygen to release energy.

Word equation for aerobic respiration.

Glucose + oxygen → carbon dioxide + water.