Biology Paper 1 Exam Preview 2024/2025: Questions and Answers, Exams of Biology

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Eukaryo)c cell Cell that has a nucleus and other membrane-bound organelles Prokaryo)c cells Gene)c material is not enclosed in a nucleus. They are much smaller An animal cell contains... Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes A plant cell contains... Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes, chloroplasts, cell wall, vacuole Func)on of nucleus Enclose gene)c material Func)on of cytoplasm Liquid where chemical reac)ons occur Func)on of cell membrane

BIOLOGY PAPER 1 EXAM

PREVIEW 2024/2025 (ACTUAL

QUESTIONS AND ANSWERS)

Control what enters and leaves the cell Func)on of mitochondria Where aerobic respira)on takes place Func)on of ribosomes Site of protein synthesis Func)on of chloroplasts Contain chlorophyll and are the site of photosynthesis Func)on of cell wall Strengthen the cell; made of cellulose Func)on of vacuole Full of cell sap; keeps the plant cells shape Differen)a)on The process of a cell becoming specialised; having a specific func)on Sperm cells adapta)ons Half the gene)c material, long tail for swimming, lots of mitochondria for energy, contain egg-diges)ng enzymes Nerve cell adapta)ons Long axons carry impulses, myelin insulates and speeds up, synapse allow impulses to move, contains egg diges)ng enzymes Muscle cell adapta)ons Can contract, lots of mitochondria, wok together Root hair cell adapta)ons Large surface area to volume ra)o, no chloroplasts Xylem adapta)ons No end walls, made from dead lignin cells Phloem adata)ons Have a companion cell to provide energy

Microscopes prac)cal Use a slide and place it in microscopes on the lowest magnifica)on. Focus the microscope while increasing the magnifica)on. Magnifica)on = Size of image/size of real object Electron microscopes Have a higher resolu)on and magnifica)on. Can see in greater detail. They are more heavy, less portable and more expensive. Bacteria Mul)ply by binary fission. About once every 20 minutes. Prac)cal: an)bio)cs and bacteria

1. Sterilise area 2.sterilise inocula)on loop using fire
2. Open agar plate near flame
3. Spread bacteria over plate
4. Place an)bio)c paper in plate
5. Incubate for a few days at 25 degrees Gametes Sex cells that contain half the number of chromosomes Chromosomes Humans have 23 pairs of chromosomes. They carry genes Cell cycle
6. Dna replicates, the cell grows and copies internal structures
7. Mitosis takes place, cell splits
8. Two iden)cal cells are formed Stem cell

An undifferen)ated cell which can give rise to more cells of the same type and can differen)ate to form other types of cells Stem cells loca)on They are found in plant meristems, embryos and in bone marrows Bone marrow transplant Treat pa)ents with leukaemia. The implanted stem cells divide to form new blood cells. Therapeu)c cloning A donor embryo is conceived to provide stem cells with the same genes for a pa)ent. Diffusion The spreading out of par)cles resul)ng in a net movement from an area with a high concentra)on to an area of low concentra)on Factors affec)ng the rate of diffusion ↑ concentra)on gradient ↑ diffusion ↑ temperature ↑ diffusion ↑ sa:v ↑ diffusion ↓ diffusion pathway ↑ diffusion Osmosis Diffusion of water from a dilute solu)on through a par)ally permeable membrane Ac)ve transport Moves substances from a more dilute solu)on to a more concentrated solu)on against the concentra)on gradient. Prac)cal: effects of osmosis

1. Cut potato into equal-sized cubes
2. Measure mass and size of the cube

3. Put potato into 10cm3 of 0.5 molar sugar solu)on
4. Put potato into 10cm3 of 0.25 molar sugar solu)on
5. Put potato into 10cm3 of water
6. Leave overnight
7. Measure mass and sizw again Tissue A group of cells with a similar structure and func)on Organ Group of )ssues working together for a specific func)on Diges)on Is the breaking down large insoluble molecules into small soluble molecules by enzymes The diges)ve system contains Mouth, oesophagus, stomach,small intes)ne, large intes)ne, liver, panaceas, rectum, duodenum Func)on of mouth Food is chewed here. Enzymes begin to break it up Func)on of oesophogus Squeezes food down using peristalsis mo)on. Func)on of stomach The diges)on of proteins begins. It contains hydrochloric acid. Churning ac)on make food into a fluid Func)on of small intes)ne

Absorbs nutrients(glucose, protein) from food. Func)on of large intes)ne Absorbs water from food Func)on of liver Produces bile Func)on of pancreas Produces enzymes Enzymes Large protein molecules that catalyse chemical reac)ons without having any chemical change to themselves. Work at an op)mum ph and temperature. Protease Breaks down proteins into amino acids. Made in the stomach, pancreas and small intes)ne. Amalayse Breaks down carbohydrates into starch. Made in the salivary glands and the pancreas. Lipease Breaks down lipids into 3 fagy acids and 1 glycerol. Made in the pancreas and small intes)ne Bile Speeds up diges)on of lipids. Stored in the gall bladder. Emulsifies the lipids to increase the surface area that enzymes can work on and nutrilaises stomach acid Hydrochloric acid Provides the op)mum ph for enzymes to work in the stomach. Prac)cal: ph and enzymes

1. Place a drop of iodine solu)on into each well of spohng )le
2. Get three test tubes and add a - 2cm3 starch solu)on b - 2cm3 amylase solu)on c - 2cm3 ph 5 buffer solu)on
3. Place the test tubes in a 30c water bath
4. Mix the solu)ons and start )mer
5. Every 30 secs add a drop of the mixed solu)on into a new well in the spohng )le
6. If starch is present it will turn blue, stop adding solu)on when it remains orange
7. Repeat using ph 6,7,8 buffers Prac)cal: starch test
8. Place 2cm3 food solu)on in a test tube
9. Add a few drops of iodine present= turn blue black not present= stay orange Prac)cal: sugar test
10. Place 2cm3 food solu)on in a test tube
11. Add 10 drops benedict's solu)on
12. Place test tube in beaker of hot water
13. Leave for 5 minutes present = turn green/red not present = stay blue Prac)cal: protein test
14. Place 2cm3 food solu)on in a test tube
15. Add 2cm3 of biurets

present = turn pink/purple not present = stay blue Prac)cal: lipid test

1. Place 2cm3 food solu)on in a test tube
2. Add 3 drops sudan iii
3. Shake gently present = red stained oil layer will float to surface not present = stay red Small intes)ne adapta)ons Villi and micro villi increase sa:v ra)o good blood supply thin membrane Right atria 4 receives deoxygenated blood from the body through the vena cava and pumps it into the right ventricle Right ventricle 5 pumps blood to lungs

Lel ventricle 6 pumps blood to body cells Lel atria 7 pumped from the pulmonary vein into the the lel ventricle Pulmonary vein 10 transfer oxygenated blood from the lungs to the heart Pulmonary artery 11 carries deoxygenated blood from the right ventricle to the lungs

Aorta 12 distributes oxygenated blood to all parts of the body through the systemic circula)on. Vena cava 3 carries deoxygenated blood from the lower half of the body to the right atrium of the heart San Controls the heart rate. Ar)ficial pacemaker can replace it. Arteries Carry high pressure blood from the heart to the organs of the body. Thick muscular wall and elas)c fibres. Capillaries

Allow oxygen and carbon dioxide to diffuse in and out of the blood stream. Very thin walls. Veins Carry blood from organs back to the heart at low pressure. Thin walls and valves. Blood contains Red blood cells, white blood cells and platelets suspended in plasma Red blood cells Transport oxygen from the lungs to the body cells. Contain haemoglobin which binds with oxygen to form oxyhaemoglobin. No nucleus and biconcave shape so more room for oxygen and larger sa:v ra)o While blood cells Form part of the immune system. Platelets Tiny fragments of cells that help blood to clot Coronary heart disease The coronary arteries supply oxygen to he heart. They can easily be blocked with fat. Sta)ns Drugs which reduce cholesterol and prevent fat build up. They are effec)ve but cause liver problems Stent A tube which unblocks the fat. But it doesn't threat underlying issue. Replacement valves Can use animal or mechanical valves. With animal they need replacing but no drugs are needed. Opposite for mechanical. Breathing system

Benign tumour Uncontrolled mitosis which causes a membrane contained membrane so it doesn't invade other parts of the body Malignant tumours Invade neighbouring )ssues and enter bloodstreams. Can be caused by gene)cs or lifestyle. Radioac)ve exposure increases the risk as t damages the dna and causes muta)ons. Communicable diseases Can be spread by pathogens such as bacteria or viruses. Non-communicable is the opposite. Structure of a leaf Epidermis Protect the leaf. Transparent and have a waxy cu)cle. Thin to fit a lot near the surface of the leaf. Palisade mesophyll Lots of chloroplasts as it is the site of photosynthisis Spongy mesophyll Contain air spaces for gas exchange. Guard cells

Open and close stomata to control gas exchange Meristem Undifferen)ated cells at the roots and shoots and the plants Transpira)on Evapora)on of water hoger = faster transpira)on dryer = faster transpira)on windy = faster transpira)on sunny = faster transpira)on Pathogens Microorganisms that cause infec)ous disease Pathogen reproduc)on Bacteria can reproduce but viruses need a host cell to reproduce. Pathogen spread Pathogens can be spread:

• in air
• in water
• by direct contact we can prevent spread by:
• washing hands
• using a condom
• clean drinking water
• vaccina)on Measles Highly infectous viral disease spread by droplets. Most children are vaccinated against it. Hiv

Caused by a virus and spread in droplets. Makes the immune system agack itself to cause damage. An)viral diseases can top reproduc)on but it is not a cure Salmonella Bacteria spread in unhygienic food. Toxins are releases and cause vomi)ng and diarrhoea. In uk chickens are vaccinated. Malaria Pro)st that uses mosquitos as a vector as it cant pass from person to person. Use insec)cide and mosquito nets to stop spread. Gonorrhoea Sexually transmiged disease that was previously treated with penicillin. Now an)bio)c resistant bacteria mean we have yo find alterna)ve treatment Pathogen barriers

• skin (produces sebum)
• nose (contains hair and mucus)
• lungs (mucus and cilia)
• stomach (acid kills bacteria) Immune system Destroys pathogen and toxins. Protect against a 2nd wave agack. White blood cells:
• ingest and destroy
• produce an)bodies
• porduce an)toxins Tobacco mosaic virus Widespread plant infec)on. Causing discoloura)on and therefore reduces photosynthesis Rose black spot

A fungus that discolours leaves, reduces photosynthesis and prevents growth. Vaccina)on Introduces small amounts of dead or inac)ve forms of a pathogen into a body do the the immune system gets used to it and can fight back if infec)on occurs as correla)ng white blood cells already exist. An)bio)cs Kill infected bactria inside the human body without harming body cells. Overuse has led to resistance. Drug tes)ng We must check the toxicity, efficacy and does of a drug.

1. On cultured calls and animals
2. On healthy humans
3. On more people to find dose Placebo Tablet or injec)on with no ac)ve drug in it. Rules out psychological effect. Double blind trail = no one knows who has placebo to prevent bias Monoclonal an)bodies Very specific an)bodies can detect hormones and treat cancer.
4. Inject mouse with an)gen
5. Extract lymphocytes from mouse
6. Select corresponding lymphocyte
7. Fuse lymphocytes with tumour cells
8. New cell divides by mitosis
9. Collect and purify an)body Plant pathogen responses

• cell wall
• waxy cu)cle

• bark on tress
• an)bacterial chemicals
• poisons
• thorns and hairs
• mimicry Photosynthisis 6co2 + 6h2o - > c6h12o6 + 6o endothermic Uses for glucose made in photosynthisis
• respira)on
• insoluble storage molecules(starch)
• converted to fats and oils
• celullose for cell wall
• to produce amino acids Prac)cal: photosynthisis

1. Put a boiling tube 10cm away from led light
2. Fill boiling tube with sodium hydrogen carbonate solu)on
3. Put a piece of pondweed in tube (cut end at top)
4. Leave for 5 mins
5. Start a )mer and count bubbles in a minute
6. Repeat at 20, 30 and 40 cm use gas syringe Light = 1/distance^ Respira)on Exothermic reac)on supplies energy Aerobic respira)on

C6h12o6 + 6o2 - > 6co2 + 6h2o

• complete breakdown Anaerobic respira)on in animals Glucose - > lac)c acid
• incomplete
• less energy Anaerobic respira)on in plants and yeast Glucose - > ethanol + carbon dioxide
• fermenta)on Effects of exercise During exercise more muscle contrac)ons so more energy needed. Oxygen runs out so anaerobic respira)on occurs. Lac)c acids fa)gues muscles Oxygen debt The amount of extra oxygen the body needs aler exercise to break down the accumulated lac)c acis Metabolism The sum of all the chemical reac)ons in the body