AQA GCSE Biology Paper 1 Flashcards

100 flashcards covering key concepts from Infection & Response, Bioenergetics, Organisation, and Plant Biology based on the provided lecture notes.

What are pathogens and what do they cause?

Microorganisms (viruses, bacteria, protists, and fungi) that cause infectious disease.

Name the four types of pathogens.

Viruses, bacteria, protists, and fungi.

How can pathogens spread?

Direct contact, water, and air (e.g., droplet infection from sneezing or coughing).

Fill in the blank: Viruses move into cells and use the cell’s biochemistry to make many copies of themselves. This leads to the cell and releasing all of the copies.

bursting

How do bacteria multiply?

Rapid reproduction by binary fission.

What do bacteria produce that can damage cells?

Toxins.

What are the two forms of fungal respiration/spread?

Single-celled fungi and hyphae; they can produce spores that spread.

List the main ways pathogens spread.

Direct contact, water, and air (including droplet infection).

What is droplet infection?

Pathogens carried in droplets expelled by sneezing, coughing, or talking and breathed in.

What is vaccination?

Injection of a harmless form of a pathogen to stimulate immunity.

What is herd immunity?

When a large proportion of the population is immune, reducing pathogen spread.

What are the symptoms of measles?

Fever and red skin rash; can lead to pneumonia, encephalitis, and blindness.

How is measles prevented?

Vaccination of young children to reduce transmission.

What are the symptoms and transmission of HIV?

Initial flu-like symptoms; then attacks the immune system, leading to AIDS; spread through sexual contact or exchange of bodily fluids.

How can HIV transmission be prevented?

Using condoms, not sharing needles, screening blood for transfusions, and antiretroviral drugs to stop replication.

What plant pathogen affects tomatoes and other species and causes leaf discolouration?

Tobacco mosaic virus (TMV); spread by contact and vectors; managed by field hygiene and resistant strains.

How can TMV be prevented?

Good field hygiene and pest control; growing TMV-resistant strains.

What are the symptoms of Salmonella infection?

Fever, stomach cramps, vomiting, and diarrhoea due to toxins.

How is Salmonella spread?

Bacteria found in raw meat and eggs; unhygienic handling.

How can Salmonella infection be prevented?

Vaccinating poultry; separate raw and cooked foods; wash hands and surfaces; cook food thoroughly.

What are the symptoms of gonorrhoea?

Thick yellow or green discharge and painful urination.

How is gonorrhoea spread and treated?

Sexual transmission; treated with antibiotics; resistance is a risk; condoms reduce spread.

What causes rose black spot and its symptoms?

A fungal disease with purple/black spots on rose leaves, reducing photosynthesis.

How is rose black spot spread and prevented?

Spores spread by water or wind; prevented with fungicides and removing affected leaves.

What is malaria and its vector?

Malaria is caused by a protist; transmitted by the female Anopheles mosquito; protists reproduce in the mosquito and enter the human bloodstream.

How can malaria be prevented?

Insecticide-treated nets, removing stagnant water, taking antimalarial drugs when traveling.

What are the components of the non-specific immune system?

Skin, nose hairs and mucus, cilia in the trachea/bronchi, and stomach acid.

What are the three roles of white blood cells in the specific immune system?

Phagocytosis, producing antibodies, and producing antitoxins.

What is an antibody and how does it help immune response?

A protein produced by B cells that binds to an antigen, clumping pathogens for easier removal.

What is the purpose of vaccination in relation to antibodies?

Vaccines stimulate white blood cells to produce antibodies against specific antigens, providing immunity.

Who discovered penicillin and why is it important?

Alexander Fleming; observed mould producing penicillin that killed bacteria, leading to antibiotics.

What are monoclonal antibodies?

Identical antibodies produced from a single hybridoma cell; bind to one specific antigen.

How are monoclonal antibodies produced (steps 1-4)?

1) Mice lymphocytes are stimulated to produce a specific antibody. 2) Fused with tumour cells to form a hybridoma. 3) Hybridoma clones produce identical antibodies. 4) Antibodies are collected and purified.

Give uses of monoclonal antibodies.

Pregnancy tests, measuring hormones/chemicals in blood, research, and treatment of some diseases (e.g., cancer).

How does a pregnancy test using monoclonal antibodies work?

hCG in urine binds to mobile antibodies with blue beads; the complex moves to the test line where stationary antibodies capture it, forming a blue line.

What are the two other major uses of monoclonal antibodies in labs and medicine?

Measuring hormones/chemicals in blood and identifying molecules on cells or tissues; treating certain diseases by targeting tumour markers.

What are the advantages and disadvantages of monoclonal antibodies?

Advantages: bind to specific cells; can treat many conditions. Disadvantages: difficult to attach to drugs; expensive; potential immune reactions; initial mouse components can trigger responses.

What are the key plant disease signs and how can you identify a plant disease?

Signs include stunted growth, spots, decay, abnormal growths, discolouration, pests. Identification via manuals, observing infected plants, and monoclonal antibody testing.

What plants and pests are specifically mentioned as learnable diseases?

Tobacco mosaic virus (TMV), black spot, and aphids.

What deficiencies affect plant growth (nitrates and magnesium)?

Nitrate deficiency causes stunted growth; magnesium deficiency causes chlorosis (loss of chlorophyll).

What are the physical plant defences against pathogens?

Waxy cuticle, cellulose cell walls, and layers of dead tissue (bark) that pathogens must breach.

What are the chemical defences in plants?

Poisons and antibacterial compounds (e.g., mint and witch hazel) to deter herbivores and pathogens.

What are some mechanical defences in plants?

Thorns/hairs; leaf drooping or curling to move away pests; mimicry and patterning to trick herbivores.

How can you test for plant pathogens using monoclonal antibodies?

Pathogens can be identified by applying monoclonal antibodies that bind to specific antigens.

What are the main roles of enzymes in digestion?

Carbohydrases break carbohydrates to sugars; proteases break proteins to amino acids; lipases break lipids to fatty acids and glycerol.

What enzyme converts starch to maltose and where is it produced?

Amylase; produced in the salivary glands, pancreas, and small intestine.

What is the active site and how does it relate to enzymes?

The region of the enzyme where the substrate binds; the lock-and-key model explains specificity.

What are the optimum conditions for most human enzymes?

Around pH 7 and about 37°C; denaturation occurs at extreme temperatures or pH.

What is the function of bile?

Alkaline to neutralise stomach acid and emulsify fats, increasing the surface area for lipase.

What are the three forms of test for macromolecules (carbohydrates, proteins, lipids) and their indicators?

Benedict’s test for sugars; Iodine for starch; Biuret test for protein; Emulsion or Sudan III for lipids.

Where is bile produced and stored, and what are its two roles?

Produced in the liver, stored in the gall bladder; neutralises stomach acid and emulsifies fats.

How do enzymes affect rate of reaction with pH and temperature?

They have optimum pH and temperature; deviations reduce rate and can denature the enzyme.

What is the role of the heart in the circulatory system?

Pumps blood around the body in a double circulatory system: to the lungs (right side) and to the rest of the body (left side).

Describe the four-chamber structure and function of the heart.

Two atria and two ventricles; valves prevent backflow; coronary arteries supply the heart muscle.

What is a pacemaker and what does it do?

A group of cells in the right atrium that initiates a heartbeat; an artificial pacemaker can regulate rhythm.

What is meant by arteries, veins, and capillaries?

Arteries carry blood away from the heart with thick muscular walls; veins carry blood to the heart with valves to prevent backflow; capillaries are thin-walled and allow diffusion near cells.

What is the function and structure of capillaries?

One cell thick walls, very permeable, allow substances to move between blood and cells.

How does gas exchange occur in the lungs?

Oxygen diffuses from alveoli to blood, carbon dioxide diffuses from blood to alveoli.

What is the function of alveoli?

Tiny air sacs with large surface area for efficient gas exchange; surrounded by capillaries and very thin walls.

How is breathing rate measured in humans?

Breaths per minute.

What controls the resting heart rate?

A pacemaker group of cells in the right atrium sets a natural rhythm.

What is the purpose of the circulatory system’s double circulation?

To separate oxygenated and deoxygenated blood and efficiently deliver oxygen to tissues.

What is the structure and function of the xylem and phloem?

Xylem transports water/minerals; phloem transports sugars; xylem is dead and hollow; phloem has sieve plates and companion cells.

What is translocation in plants?

Movement of sugars in the phloem from leaves to other parts of the plant.

What is transpiration?

Loss of water vapour from leaves via stomata as part of gas exchange.

What factors affect transpiration rate?

Temperature, humidity, wind, and light intensity.

What is a potometer used for?

Measuring the rate of transpiration by tracking a bubble’s movement in a capillary tube.

What are guard cells and what do they do?

Kidney-shaped cells that surround stomata; regulate opening/closing to control gas exchange and water loss.

How do light and wind affect stomata and transpiration?

More light opens stomata (more transpiration); increased wind removes surrounding water vapour, increasing transpiration.

What is osmosis?

Movement of water across a semi-permeable membrane from high to low water potential; passive process.

What is osmosis in plants and why is turgor important?

Water enters plant cells by osmosis, creating turgor that keeps leaves/ stems rigid.

What happens to plant cells in hypertonic and hypotonic solutions?

Hypertonic: water leaves; hypotonic: water enters; isotonic: no net movement.

What are the two main types of transport across membranes besides diffusion and osmosis?

Active transport and osmosis; active transport uses energy to move against a concentration gradient.

Where does active transport occur in plants and animals?

In root hairs for minerals; in the gut for glucose/amino acids against gradient.

What is diffusion and which substances can diffuse across cell membranes?

Passive spread of particles from high to low concentration; small molecules like O2, CO2, and some urea diffuses; large molecules like starch and proteins cannot.

What is the difference between diffusion rate and temperature?

Higher temperature increases kinetic energy, increasing diffusion rate.

What is the difference between single-celled and multicellular organisms’ exchange needs?

Single-celled organisms rely on diffusion due to large surface area-to-volume ratio; multicellular organisms require specialised exchange surfaces (lungs, gills, small intestine) due to smaller surface area-to-volume ratio.

What is standard form and why is it used in science?

A way to express very large or very small numbers by keeping numbers between 1 and 10 multiplied by a power of 10.

How do you calculate the area of an inhibition zone in antibiotic testing?

Use the formula for the area of a circle: πr^2.

How are bacteria grown in labs and why must aseptic technique be used?

Grown on nutrient broth or agar; sterile equipment and sterile plates prevent contamination and ensure valid results.

Why are Petri dishes stored upside down during incubation?

To prevent condensation from dripping onto the agar surface and disturbing growth.

What temperature is used to incubate bacterial cultures in educational settings?

About 25°C to reduce risk to humans.

What is binary fission and how fast can bacteria divide under ideal conditions?

A bacterium splits into two; under ideal conditions, roughly every 20 minutes.

How can antibiotics be tested for effectiveness using bacteria?

Discs soaked with different antibiotics placed on an agar plate with bacteria; measure inhibition zones.

What information does the size of the inhibition zone provide?

The effectiveness of the antibiotic; larger zones indicate more effective bacterial kill.

What is cell differentiation?

The process by which cells become specialised through turning on or off certain genes.

What are stem cells and what is the difference between embryonic and adult stem cells?

Stem cells can differentiate into multiple cell types. Embryonic stem cells can become any cell type; adult stem cells are more limited (e.g., bone marrow). Meristems in plants retain this ability throughout life.

What is therapeutic cloning?

Producing an embryo with the same genetic makeup as the patient to obtain stem cells that won’t be rejected.

What are some ethical concerns related to stem cell research?

Destruction of embryos; questions about use of surplus embryos; religious or personal objections.

What is mitosis and what role does it play?

A stage of the cell cycle where chromosomes are separated to form two identical cells; essential for growth, development, and tissue repair.

What are chromosomes and genes?

Chromosomes are DNA molecules; genes are small DNA sections that code for proteins.

How many chromosomes do humans have in somatic cells and sex cells?

46 in somatic cells (23 pairs); 23 in sex cells (gametes).

What is a plasma and its role in blood?

Liquid that carries red blood cells, white blood cells, platelets, nutrients, hormones, and wastes.

What are red blood cells designed to do?

Carry oxygen using haemoglobin; bioconcave shape increases surface area; lack a nucleus to maximize space.

What are white blood cells and what types exist?

Part of the immune system; types include those that produce antibodies, those that engulf pathogens, and those that produce antitoxins.

What do platelets do?

Aid in blood clotting to form a scab and seal wounds.

What is coronary heart disease and how can it be treated?

Blockage of coronary arteries leading to reduced oxygen to the heart; treated with stents or statins; valve replacements or heart transplant in severe cases.

What are stents and what are their risks?

Metal mesh tubes to keep arteries open; risks include thrombosis and potential infection.

What are statins and what do they do?

Drugs that lower LDL cholesterol and can raise HDL cholesterol; may have side effects and require ongoing use.

What is a heart valve replacement and what are the options?

Biological valves from animals or mechanical valves; biological valves tend to last shorter but require less long-term medication; mechanical valves last longer but require prolonged blood-thinning drugs.