Bio paper 1

Cell types & structures -

What is the main structural difference between prokaryotic + eukaryotic cells?

Eukaryotic cells have a true nucleus enclosed by a membrane and ogranelles such as mitochondria and chloroplasts. Prokaryotic cells have no nucleus - their DNA is free in the cytoplasm - and they lack membrane bound organelles.

Cell types & structures -

Name five organelles found in both plant and animal cells + describe their functions.

Nucleus - contains DNA; controls cell activity

Cytoplasm - site of most chemical reactions

Cell membrane - controls entry + exit of substances

Mitochondria - site of aerobic respiration

Ribosomes - site of protein synthesis

Cell types & structures -

What additional structures are found in plant cells but not animal cells, + what are their roles?

Cell wall (cellulose) - provides support + structure

Chloroplasts - contains chlorophyll for photosyntheiss

Permanent vacuole - filled w/ cell sap; maintains turgor pressure

Cell types & structures -

What are plasmids, + where are they found?

Plasmids - small circular loops of DNA found in prokaryotic cells such as bacteria. They carry additional genes, e.g. for antibiotic resistance.

Microscopy -

Compare light + electron microscopes in terms of magnification + resolution.

Light microscope - Max 2000x magnification; lower resolution (200 nanometers).

Electron microscope - Over 1 000 000x magnification; higher resolution (0.2 nanometers); can view ultrastructure like ribosomes + internal membranes.

Microscopy -

What is the equation for calculating magnification?

Magnification = image size/ actual size

Make sure all units are the same.

Microscopy -

Why do we use stains in microscopy?

To highlight different structures in cells, to make them more visible under a microscope.

Cell specialisation -

What is meant by “cell differentiation”?

The process by which unspecialised cells develop → specialised cells w/ specific structures + functions.

Cell specialisation -

Give three examples of specialised animal cells + how their structure helps their function.

Sperm cell - long tail for mobility, mitochondria for energy, acrosome w/ enzymes to penetrate egg.

Nerve cell - Long to carry impulses over distances; branches for connections.

Muscle cell - Lots of mitochondria for energy; can contract to move.

Cell specialisation -

Give two examples of specialised plant cells.

Root hair cell - Large surface area for water/ mineral uptake.

Xylem cell - Hollow + strengthened w/ lignin for water transport.

Cell division & the cell cycle -

What is the purpose of mitosis?

To produce two genetically identical daughter cells for growth, repair, + asexual reproduction.

Cell division & the cell cycle -

What is the purpose of mitosis?

To produce two genetically identical daughter cells for growth, repair, + asexual reproduction.

Cell division & the cell cycle -

Describe the main stages of the cell cycle.

Growth phase - cell increases in size; organelles + DNA are duplicated.

Mitosis - nucleus divides

Cytokinesis - cytoplasm + cell divide into two

Cell division & the cell cycle -

Why is it important that the daughter cells produced by mitosis are identical?

To ensure genetic consistency for proper function in body tissues + organs.

Stem cells -

What are stem cells?

Undifferentiated cells that can divide to produce more stem cells / differentiate → specialised cells.

Stem cells -

Where are stem cells found in humans?

Embryonic stem cells - can become most cell types.

Adult stem cells - limited to certain cells like blood cells.

Stem cells -

How can stem cells be used in medicine?

To replace damaged cells. Stem cells may be grown into specific tissues for transplantation.

Stem cells -

What are some risks + ethical concerns of stem cell use?

Ethical - use of embryos destroys potential life.

Medical - risk of rejection, mutations, / infection.

Stem cells -

What are meristems + their role in plants?

Regions in plants that contain unspecialised cells that can divide + differentiate throughout the plant’s life.

Transport in cells -

Define diffusion + give one example in the human body.

The movement of particles from an area of high to low concentration. E.g. oxygen diffusing from alveoli into red blood cells.

Transport in cells -

What factors affect the rate of diffusion?

Concentration gradient, temperature, surface area, + diffusion distance.

Transport in cells -

Define osmosis.

The diffusion of water from a dilute solution to a more concentrated solution through a partially permeable membrane.

Transport in cells -

Describe an example of osmosis in a plant cell.

Water moves into the plant cell, increasing turgor pressure + keeping the plant rigid.

Transport in cells -

What is active transport + how does it differ from diffusion?

Movement of substances against a concentration gradient using energy from respiration. Unlike diffusion, it requires ATP.

Transport in cells -

Give two examples of active transport.

• Absorption of minerals by root hair cells in plants

• Reabsorption of glucose in the kidney tubules in humans

Principles of Organisation -

What is the hierarchical organisation of living organisms?

Cells → Tissues → Organs → Organ systems → Organism

Principles of Organisation -

Define a tissue + give an example.

A group of similar cells working together to perform a specific function, e.g. muscular tissue contracts to bring movement.

Principles of Organisation -

What is an organ system?

A group of organs working together to carry out a particular function, e.g. the digestive system.

The Human Digestive System -

What is the function of the digestive system?

To break down large, insoluble molecules into smaller, soluble molecules for absorption into the blood.

The Human Digestive System -

Name the main organs of the digestive system in order.

Mouth → Oesophagus → Stomach → Small intestine → Large intestine → Rectum → Anus (Liver + pancreas - accessory organs)

The Human Digestive System -

What is the role of the mouth in digestion?

Mechanical breakdown by teeth + chemical digestion by amylase (saliva).

The Human Digestive System -

What happens in the stomach during digestion?

Proteins begin digestion by pepsin (a protease); hydrochloric acid kills bacteria + provides the optimum pH (around 2).

The Human Digestive System -

What does the pancreas do?

Produces digestive enzymes (amylase, protease, lipase) released into the small intestine.

The Human Digestive System -

What is bile, + what are its functions?

Bile’s made by the liver, stored in the gall bladder. It emulsifies fats + neutralise stomach acid to provide alkaline conditions for enzymes in the small intestine.

Enzymes -

What are enzymes?

Biological catalysts that speed up reactions without being used up.

Enzymes -

What is the “lock and key” model?

The enzyme has a specific active site that only fit a complementary substrate - like a lock fits a key.

Enzymes -

What affects enzyme activity?

Temperature + pH.

Enzymes -

What happens to enzymes at high temperatures / extreme pH?

The enzyme becomes denatured - the active site changes shaoe + no longer binds the substrate.

Enzymes -

Which enzymes break down carbohydrates, proteins, + lipids?

Carbohydrase (amylase) - Breaks starch → glucose.

Protease - Breaks proteins → amino acids.

Lipase - Breaks lipids → fatty acids + glycerol.

The Circulatory System (heart & blood) -

What type of circulatory system do humans have?

Double circulatory system - one loop to the lungs, one to the body.

The Circulatory System (heart & blood) -

Describe the structure + function of the heart.

Four chambers: right atrium → right ventricle → lungs (via pulmonary artery); then left atrium → left ventricle → body (via aorta). The valves prevent backflow.

The Circulatory System (heart & blood) -

What is the role of the coronary arteries?

Supply oxygenateed blood to the heart muscle.

The Circulatory System (heart & blood) -

What is the pacemaker of the heart + where is it located?

A group of cells in the right atrium that control heart rate via electrical impulses.

The Circulatory System (heart & blood) -

Name the three types of blood vessels + their characteristics.

Arteries - Thick, muscular walls; carry blood away from heart under high pressure.

Veins - Thinner walls, valves; carry blood back to heart.

Capillaries - Very thin walls for efficient diffusion.

The Circulatory System (heart & blood) -

Name the four components of blood + their functions.

Red blood cells - Carry oxygen (contains haemoglobin).

White blood cells - Defend against infection.

Platelets - Help blood clot.

Plasma - Transports substances like glucose, CO2, hormones, etc.

Cardiovascular disease -

What causes coronary heart disease?

Build-up of fatty material in coronary arteries, reducing blood flow to the heart muscle.

Cardiovascular disease -

Name two treatments for coronary heart disease.

Stents - Keep arteries open.

Statins - Lower cholesterol levels in the blood.

Cardiovascular disease -

What are the risks of faulty heart valves + how are they treated?

Can leak / not open properly; treated w/ mechanical / biology replacement valves.

Cardiovascular disease -

What is an artificial pacemaker?

A device implaneted under the skin to regulate the heart rate using electrical impulses.

Cardiovascular disease -

What is artificial blood used for?

To replace lost fluid volume temporarily when someone loses a lot of blood, giving time for transfusion.

Health & Disease -

What is a communicable disease?

A disease that can be spread between individuals, caused by pathogens.

Health & Disease -

Give examples of non-communicable diseases.

Coronary heart disease, cancer, diabetes.

Health & Disease -

How can different diseases interact in the body?

One disease can make you more susceptible to others, e.g. HIV weakens immune system → more infections.

Health & Disease -

What factors can affect your health?

Diet, stress, lifestyle, access to healthcare, genetic disorders.

Cancer -

What is cancer?

Uncontrolled cell division forming a tumour.

Cancer -

What is the difference between benign + malignant tumours?

Benign - Doesn’t spread; usually harmless.

Malignant - Invades other tissues + spreads (metastasis); cancerous

Cancer -

Name some risk factors for cancer.

Smoking (lung cancer), UV exposure (skin cancer), viruses (e.g. HPV → cervical cancer), genetics.

Plant tissues, organs & transport -

Name the main tissues in a leaf + their functions.

Epidermis (upper/lower): Transparent, protective.

Palisade mesophyll: Packed w/ chloroplasts for photosynthesis.

Spongy mesophyll: Air spaces for gas exchange.

Xylem: Transports water + minerals.

Phloem: Transports sugars (translocation).

Stomata & guard cells: Control gas exchange + water loss.

Plant tissues, organs & transport -

What is the function of xylem vessels?

Transport water + minerals from roots to leaves (via transpiration stream).

Plant tissues, organs & transport -

What is the function of phloem vessels?

Transport dissolved sugars from leaves to the rest of the plant - both directions (translocation).

Plant tissues, organs & transport -

What is transpiration?

Loss of water vapour from the leaves through the stomata, driving the uptake of water via xylem.

Plant tissues, organs & transport -

What factors affect the rate of transpiration?

Temperature, humidity, air flow, light intensity.

General Knowledge -

What are communicable diseases?

Diseases that can be spread from one organism to another, caused by pathogens such as bacteria, viruses, fungi, + protists.

General Knowledge -

What is a pathogen?

A microorganism that causes disease.

General Knowledge -

Name the four main types of pathogens.

Bacteria, viruses, fungi, + protists.

Bacterial + Viral Diseases -

How do bacteria cuase disease?

By producing toxins that damage tissues + make us feel ill.

Bacterial + Viral Diseases -

How do viruses cause disease?

They invade cells + reproduce inside them, causing the cell to burst + die.

Bacterial + Viral Diseases -

Name + describe symptoms of one bacterial disease in humans.

Salmonella - Causes food poisoning, symptoms include fever, stomach cramps, vomiting, + diarrhoea.

Bacterial + Viral Diseases -

How is salmonella spread + how is it controlled?

Spread through contaminated food. In the UK, poultry is vaccinated against it.

Bacterial + Viral Diseases -

Name + describe a viral disease in humans.

Measles - Spread by droplets; symptoms include fever + red skin rash. Can be serious, leading to pneumonia / brain infection.

Bacterial + Viral Diseases -

How is measles prevented?

Vaccination, especially as part of the MMR vaccine.

Bacterial + Viral Diseases -

What is TMV and how does it affect plants?

Tobacco Mosaic Virus - causes a mosaic pattern on leaves, reducing photosynthesis + stunting growth.

Fungal + Protist Diseases -

Name one fungal disease in plants.

Rose black spot - causes black / purple spots on leaves, which drop off, reducing photosynthesis.

Fungal + Protist Diseases -

How is rose black spot spread + controlled?

Spread by water / wind; controlled using fungicides + removing affected leaves.

Fungal + Protist Diseases -

Name a protist disease + how it’s transmitted.

Malaria - caused by a protist spread by mosquito vectors.

Fungal + Protist Diseases -

Describe the symptoms + prevention of malaria.

Repeating fever cycles; prevented by insecticides, mosquito nets, + removing stagnant water.

Human Defences -

Name the body’s non-specific defence systems against pathogens.

Skin - barrier + produces antimicrobial secretions.

Nose - traps pathogens w/ mucus + hairs.

Trachea/Bronchi - mucus + cilia to sweep pathogens away.

Stomach - hydrochloric acid kills pathogens.

Human Defences -

What is the role of white blood cells in the immune system?

Phagocytosis - ingest + destroy pathogens.

Antibody production - specific to each pathogen.

Antitoxin production - neutralise toxins.

Vaccination + Drugs -

What is a vaccine + how does it work?

A small amount of dead / inactive pathogen introduced into the body to stimulate white blood cells to produce antibodies.

Vaccination + Drugs -

What are the advantages of vaccination?

Prevents illness, reduces spread in the population (herd immunity).

Vaccination + Drugs -

What are the disadvantages of vaccination?

May cause side effects, doesn’t always give complete immunity.

Vaccination + Drugs -

What are antibiotics + what are they used for?

Drugs that kill / inhibit the growth of a bacteria, but not viruses.

Vaccination + Drugs -

Why don’t anitbiotics work on viruses?

Because viruses live inside cells, making it hard to target them w/out harming body cells.

Vaccination + Drugs -

What is antibiotic resistance + why is it a concern?

When bacteria mutate + survive antibiotic treatment, making infections harder to treat.

Drug Development -

Where were some modern drugs originally extracted from?

Aspirin - willow tree

Penicillin - mould (Penicillin notatum)

Drug Development -

What are the stages of drug-testing?

Preclinical testing - on cells, tissues, animals

Clinical trials (phase 1) - on healthy volunteers for safety

Clinical trials (phase 2 & 3) - on patients to test effectiveness, dosage, side effects

Double-blind trials - neither patient nor doctor knows who has placebo

Drug Development -

What is a placebo + why is it used?

A substance w/ no active ingredient used in trials to test if the real drug has an actual effect.

Photosynthesis -

What is the word equation for photosynthesis?

Carbon dioxide + Water → Glucose + Oxygen

Photosynthesis -

What is the balanced symbol equation for photosynthesis?

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Photosynthesis -

Where in a plant cell does photosynthesis take place?

In the chloroplasts, which contain chlorophyll to absorb light energy.

Photosynthesis -

Why is photosynthesis important to life on Earth?

It produces oxygen for respiration + glucose for energy in food chains.

Limiting Factors of Photosynthesis -

What are the three main limiting factors of photosynthesis?

Light intensity, Carbon dioxide concentration, Temperature.

Limiting Factors of Photosynthesis -

How does light intensity affect the rate of photosynthesis?

As light increases, so does the rate - up to a point. After that, another factor becomes limiting.

Limiting Factors of Photosynthesis -

How does temperature affect photosynthesis?

It increases rate until enzymes denature at high temperatures, causing the rate to fall.

Limiting Factors of Photosynthesis -

How does CO2 concentration affect photosynthesis?

More CO2 increases the rate, but eventually levels off when another factor limits the rate.

Limiting Factors of Photosynthesis -

How can farmers increase the rate of photosynthesis in greenhouses?

By using artificial light, heaters, + CO2 enrichment to optimise conditions.

Photosynthesis Required Practical -

What is the dependent variable in the photosynthesis practical?

The number of oxygen bubbles produced (rate of photosynthesis).

Photosynthesis Required Practical -

What is the independent variable?

The distance of the light source from the pondweed.

Photosynthesis Required Practical -

What are the control variables in this experiment?

Temperature, concentration of CO2, amount of pondweed, water volume.

Photosynthesis Required Practical -

Why is sodium hydrogen carbonate added to the water?

To provide a consistent source of carbon dioxide for photosynthesis.