Biology PAPER one.2025 with answers., Exams of Biology

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Biology PAPER 1.

"An explanation answer that makes reference to five of the following points

• temperature increases (kinetic) energy / particle movement / more collisions / eq (1)
• difference in concentration / concentration gradient increases rate of movement (1)
• short(er) distance increases diffusion /eq (1)
• surface area to (volume ratio) increases diffusion (1)
• mass / size of particle smaller particles move faster (1)
• larger particles / charged particles cannot pass through cell membrane (1)
• (increased) oxygen / ATP / respiration / energy for active transport (1) - CORRECT ANSWER Substances move in and out of cells by a variety of mechanisms. Explain the factors that affect the rate of movement of substances into and out of cells. [5]" "An answer that makes reference to the four of the following points
• diffusion passive (1)
• diffusion from high concentration to low / requires concentration gradient (1)
• active transport requires ATP / energy/ oxygen / respiration (1)
• active transport requires membrane / carrier proteins (1)
• diffusion can take place in non-living systems (1) - CORRECT ANSWER Describe the differences between diffusion and active transport. [4]" "An answer that makes reference to two of the following points:
• diagram 2 / Klinefelter has an extra chromosome / has 47 (1)
• X chromosome / sex chromosomes are different / eq (1) - CORRECT ANSWER Describe the difference between the karyotype in Diagram 1 and the karyotype in Diagram 2. [2]" "An answer that makes reference to the following points:
• mutation (1)
• failure of chromosomes to separate (1)
• during meiosis / gamete formation (1) - CORRECT ANSWER Suggest how the karyotype in Diagram 2 may be caused. [2]" "An answer that makes reference to two of the following points:
• supplies glucose / sucrose / sugar / carbohydrate / nutrients (1)
• respiration / energy / ATP (1)
• supplies amino acids (1)
• make protein (1)
• supplies water (1)
• cell elongation / eq (1) - CORRECT ANSWER Pollen grains are deposited on the stigma and grow tubes down the style. Suggest how style tissue helps the tube to grow. [2]" "!RATE OF CHANGE!

"An answer that makes reference to

• engulf / ingest / eq bacteria / pathogen / microbe / eq (1)
• digest / break down (1)
• enzymes (1) - CORRECT ANSWER Describe the function of this cell in defending the body from infection. [2]" "rate of change formula - CORRECT ANSWER change in value/time" "A description that makes reference to the following points:
• prevent backflow of blood /one way flow /eq (1)
• (from arteries) into ventricle/ ventricles (10 - CORRECT ANSWER Describe the function of the semi-lunar valves. [2]" "An explanation that makes reference to the following points:
• so that oxygenated and deoxygenated blood do not mix / as left hand side now contains oxygenated blood from lungs / eq (1)
• so that oxygenated blood can be pumped around body / so deoxygenated blood does not go round body / so oxygenated blood does not go to lungs / eq (1) - CORRECT ANSWER In the heart of a foetus, the two upper chambers (atria) are linked by a hole so that blood can pass between them. (i) Explain why this hole is normally closed before the baby is born. [2]" "An explanation that makes reference to three of the following points:
• may appear blue / lack colour / not survive / shortness of breath/ eq (1)
• as less oxygen (transported from heart to body) / deoxygenated blood goes to body / eq (1)
• less (aerobic) respiration (1)
• less energy / less ATP/ eq (1) - CORRECT ANSWER Sometimes the hole does not close. Explain what effect this will have on the baby. [3]" "new-old/change x 100 - CORRECT ANSWER Percentage change formula" "• 2.2 - 1.25 =
• 0.95 ÷ 1.25 = 0.
• × 100 = 76% - CORRECT ANSWER Calculate the percentage increase in mass of ethanol produced by GM yeast compared to normal yeast after 1 day. [2]"

1. alveoli + increase surface area
2. (alveoli) thin / one cell thick / short diffusion distance
3. capillary (wall) is thin / one cell thick / short diffusion distance
4. capillary / blood / maintains concentration gradient / diffusion gradient

5. moist / allows gases to dissolve - CORRECT ANSWER Explain, with reference to features shown in the diagram, how lung tissue enables efficient gas exchange. [4]" "1. (leaf has) large surface area
6. thin / short diffusion distance
7. stomata / allows gases in/out / diffusion
8. spongy mesophyll + increase surface area / gas diffusion / gas movement / air movement
9. moist / allows gases to dissolve - CORRECT ANSWER Explain how the structure of a leaf is adapted for efficient gas exchange. [4]" "1. less (kinetic) energy at low temperatures
10. fewer collisions / less movement at low temperatures
11. enzyme denatures
12. changes active site / eq
13. substrate can no longer bind / eq - CORRECT ANSWER Explain how changes in temperature affect the activity of an enzyme. [4]" "An explanation that makes reference to two of the following points:

• fast
• no brain involvement / no thought / automatic /involuntary
• less damage / harm - CORRECT ANSWER Explain the advantage of a withdrawal reflex when a finger touches a hot object. [2]" "Remember to use these key words:
• survives
• less competition
• mutation
• reproduce

Suggest why the large ground finch is found on Fernandina but the cactus finch is not. [2]" "- (more) light into eye / retina

• to see danger / be more aware of surroundings
• more blood to lungs
• more blood to (leg) muscles / blood diverted to (leg) muscles
• more oxygen (to muscles)
• more glucose (to muscles / in blood)
• more respiration / less anaerobic respiration / less lactic acid produced
• more ATP / energy
• run faster / escape / contract muscles more / eq - CORRECT ANSWER Adrenaline is released into the blood when there is danger. The list gives the effects of adrenaline on different parts of the body.
• dilates the pupil in the eye
• increases heart rate
• narrows small arteries in the intestine
• converts glycogen into glucose in the liver Explain the advantages of these effects to a person in danger [5]" "An explanation that makes reference to four of the following points:
• large surface area (1)
• microvilli (1)
• capillaries / blood supply to maintain concentration gradient / diffusion gradient (1)
• absorb digested food / molecules / vitamins / minerals / correct named molecule / eq (1)
• lacteal to absorb fats / correct vitamin / transport fats / eq (1)
• thin wall / one cell thick / capillaries close to surface (1)
• so short diffusion path / rapid diffusion / rapid active transport (1) - CORRECT ANSWER Explain how the undamaged villi are adapted for their function. [4]" "An answer that makes reference to five of the following points:
• more (capillaries to transport) oxygen / glucose (1)
• more (aerobic) respiration / less anaerobic respiration (1)
• more ATP/ more energy (1)
• (more) muscle contraction (1)
• less lactic acid (1)

• effective for long distance events / ineffective for power events / type of performance not specified /only leg muscle sampled / eq(1)
• other factor(s) / age / lung (capacity) / heart (rate) named other factors affect performance (1)
• need to test more than one person / not repeated / eq (1) - CORRECT ANSWER The scientist concludes that training improves the athletic performance. Discuss this conclusion. [5]" "An answer that makes reference to four of the following points:
• greater increase in testosterone in R / smaller increase in S /eq (1)
• R male/S female/eq(1)
• greater increase in oestrogen in S / less increase in R /eq (1)
• more muscle / deeper voice / beard in R/ eq (1)
• wider hips / breasts / in S (1)
• body hair / growth spurt / eq (1)
• gamete / sperm / egg production / start to menstruate (1)
• secondary sexual characteristics (1) - CORRECT ANSWER Explain how the changes in hormone concentrations affect the development of each child. [4]" "1. stomata;

2. open in light / close in dark;
3. carbon dioxide in / oxygen out;
4. prevent water loss / transpiration / evaporation; - CORRECT ANSWER Explain the role of cell D in controlling gas exchange in the leaf. [3]" "1. xylem only;
5. transport mineral ions / named mineral ion / minerals / ions / salts / eq;
6. transport water; 4. to leaves / leaf - CORRECT ANSWER Describe the function of the tissue labelled E. [3]" "(animal response)
7. uses nerves / neurones;
8. involves eyes / muscles / brain / eq;
9. electrical / uses impulses / eq;
10. faster / nerve transmission faster;
11. short duration; (plant response)
12. phloem / cells
13. growth / stem
14. auxin / chemical / hormone / growth regulator
15. response is slower
16. long duration - CORRECT ANSWER Describe the differences between an animal response to light and a plant response to light. [4]"

• 44 ÷ 432 × 100=

• allow 10.2 / 10.19 /10.185/ 10.1852/ 10.18519 - CORRECT ANSWER Calculate the percentage increase in the number of seeds that germinate in wet and cold conditions compared to the number of seeds that germinate in wet and warm conditions. [2]" "A description that makes reference to two of the following points:
• ovule becomes seed (1)
• ovule wall becomes seed coat/testa (1)
• ovary becomes fruit (1) - CORRECT ANSWER Describe what happens to the structures in part C after fertilisation. [2]" "An answer that makes reference to two of the following points:
• in warm (and wet) conditions there are more fungi / bacteria/ microbes / eq (1)
• so seeds are diseased or contents digested / consumed / seeds killed (by fungi /bacteria /microbes / eq) / eq (1)
• enzymes are activated in storage (1)
• seeds have (already) started to germinate in storage (1) - CORRECT ANSWER Suggest why fewer seeds germinate when they are stored in wet and warm conditions than in the other conditions. [2]" "An answer that makes reference to two of the following points:
• Temperature
• Blood glucose levels.
• Blood pH levels.
• Water concentration/potential. - CORRECT ANSWER Homeostasis is defined as the control of a constant internal environment. List two examples of conditions the body aims to keep constant. [2]" "An answer that makes reference to two of the following points:
• Movement of water from area of high water potential/high concentration. (1)
• To an area of lower/low water potential/low concentration. (1)
• Across a partially/semi-permeable membrane. (1) - CORRECT ANSWER What is mean by the term osmosis? [3]" "An answer that makes reference to two of the following points:
• increased heart rate
• increased breathing rate
• increased blood flow to muscles - CORRECT ANSWER What effects might a surge in adrenaline have on the body? [3]" "An answer that makes reference to two of the following points:
• Different strains of bacteria.
• Strains due to mutation.
• Antibiotics kill less resistant/less adapted strains of bacteria.
• Only strains that are resistant survive.
• Resistant strains pass on alleles to next generation.

• Antibiotics create selection pressure (or equivalent). - CORRECT ANSWER Explain how antibiotic resistance may arise in a population of bacteria? [4]" "An answer that makes reference to two of the following points:
• circular muscles relax
• radial muscles contract
• pupil dilates - CORRECT ANSWER Explain how the iris controls the diameter of the pupil in dim light. [3]" "An answer that makes reference to two of the following points:
• circular muscles contract
• radial muscles relax
• pupil constricts - CORRECT ANSWER Explain how the iris controls the diameter of the pupil in bright light. [3]" "- lens flat
• ciliary muscles relax
• suspensory ligaments pulled tight - CORRECT ANSWER Focusing on a distant object" "- lens more convex (rounded)
• ciliary muscles contract
• suspensory ligaments slack - CORRECT ANSWER Focusing on a near object" "Might improve yield of crop. Might improve taste of crop. May be more resistant to weather. May be more resistant to disease. - CORRECT ANSWER List three reasons a farmer might want to selectively breed their crops. [3]" "May increase yield of milk or meat for farmers. May increase profit. May be able to improve nutritional value of a food. But increases risk of inheriting genetic diseases. Cost of selective breeding may outweigh benefit. Some consider practice of selective breeding cruel and unethical. - CORRECT ANSWER Evaluate the various benefits and drawbacks of using selective breeding in livestock animals. [4]" "An explanation that makes reference to two of the following
• as age increase higher incidence of cancers /eq (1)
• as cells more likely to mutate /eq (1)
• smoked for longer period / eq (1)
• weak immune system / eq(1) - CORRECT ANSWER Suggest why age might affect the likelihood of dying from lung cancer. [2]"

• characteristics
• offspring
• continued - CORRECT ANSWER Complete the passage by writing a suitable word for each of the spaces. [4] Selective breeding involves _____________ choosing organisms with desired _____________. These organisms are allow to breed and produce _____________. The process is _____________ for several generations." "- respiration / movement / heat loss
• egested / undigested / faeces / not absorbed / not assimilated
• excretion / urine / urea
• uneaten / bone / teeth / fur
• death / decomposition - CORRECT ANSWER Explain why a large percentage of the energy in rabbits is not available for growth in owls. [3]" "1. temperature
• affects enzymes

2. water / moisture

• solvent / activates enzymes / dissolve chemicals / reactions

3. oxygen

• respiration

4. (sun)light

• phytochrome

5. pH

• affects enzymes - CORRECT ANSWER The scientists conclude that pollution reduces the growth of shoots by affecting cell division. ii) To make sure their conclusion is valid, the scientists control abiotic variables while the seeds are germinating. Discuss two abiotic variables that the scientists should control. [4]" "- hyphae / mycelium
• enzymes / named enzyme
• extracellular digestion / digestion outside fungus
• absorption / absorbed
• saprotrophic / saprophytic / saprobiontic - CORRECT ANSWER d) The corn becomes infected by a fungus. i) Explain how this fungus feeds on the corn. [3]"

"age / species / type / variety / size / mass - CORRECT ANSWER State one biotic factor that the scientists should control. [1]" "- restriction to (cut/eq) DNA / gene / allele / plasmid

• ligase to (join/eq) DNA / gene / allele / plasmid - CORRECT ANSWER Describe the role of enzymes in genetic modification. [2]" "- vasodilation
• (more) blood to surface / skin
• heat loss / cooling / prevents overheating
• radiation / convection
• affect enzymes - CORRECT ANSWER Explain these changes in diameter and blood flow when moving from a cold environment to a warm environment. [4]" "- genes / alleles / chromosomes
• (difference in) nutrition / diet / quality of food / quantity of food
• (difference in) metabolism / metabolic rate / respiration
• hormones / named hormones
• osteoporosis / less bone mass (in women) - CORRECT ANSWER Suggest two reasons why the mean height for males is greater than the mean height for females. [2]" "- pull (rubber) sheet down / pull ring down - CORRECT ANSWER State how the teacher could demonstrate breathing in using this model. [1]" "- (no) photosynthesis
• remove starch / destarch / cannot make starch
• respiration - CORRECT ANSWER Explain why the student keeps all three plants in the dark for 24 hours at the beginning of the investigation. [2]" "- fewer amino acids for growth / protein synthesis
• less glucose / lipid / for energy / respiration / ATP
• less vitamins / minerals / named vitamin or mineral for correct function of named vitamin or mineral
• less absorption of digested food / molecules / vitamins / minerals / correct example - CORRECT ANSWER Explain why children with untreated coeliac disease may grow more slowly and become tired more easily than children with coeliac disease. Use information from the diagram and your own knowledge to support your answer. [4]" "- show photosynthesis can occur with CO₂ present / show difference between X and Y is due to CO₂

• less bioaccumulation of pesticides / less evolution of resistance to pesticides / no pesticide remaining in soil
• pest resistant crops do not affect non-target species / pollinators
• weedkiller kills weeds but not (GM) crops / easier to remove weeds
• less spread of viruses to other species / crops Points against GM:
• gene transfer to other species / (cross) pollinate with other species
• outcompete native species / affect food chains
• reduction in insect populations
• requires herbicide use / more use of herbicides - CORRECT ANSWER Discuss these opinions for and against the use of GM crops. [4]" "- eats plants / produced
• cannot digest parts / (primary consumer) produces more faeces / more inedible parts / more waste egested - CORRECT ANSWER Assimilation efficiency is the percentage of food that is eaten and not egested as faeces. Explain why the assimilation efficiency of a primary consumer is less than the assimilation efficiency of a secondary consumer. [2]" "- more respiration / higher metabolic waste
• maintain body temperature / more movement / activity
• heat loss - CORRECT ANSWER The production efficiency of an animal is the percentage of assimilated food that is made into new biomass. Suggest why there is a difference in the production efficiency of the mammal and the snail. [2]" "- less oxygen
• (less) respiration
• (less) energy / ATP - CORRECT ANSWER Explain why bursting of red blood cells affects the development of a foetus. [2]"

"- DNA unzips / separates / one strand copied

• complementary / base pairing
• template
• mRNA produced
• transcription - CORRECT ANSWER The dominant allele codes for the production of the protein that will act as an antigen. Describe how the dominant allele leads to the production of RNA during protein synthesis. [3]" "- no nucleus / DNA / no ribosomes / mitochondria - CORRECT ANSWER Give the reason why proteins cannot be made by red blood cells. [1]" "- memory cells
• remain in mother's blood
• recognise / identify antigen / binds with antigen
• more antibodies produced / produced faster / sooner
• secondary immune response - CORRECT ANSWER Explain why the concentration of the rhesus antibody in the mother's blood rises quickly to harmful levels if she has a second child who is Rhesus positive. [3]" "- higher when temperature increases / lower when temperature decreases
• more (kinetic) energy of water molecules / particles
• increased diffusion / more liquid becomes gas - CORRECT ANSWER Explain the changes in the rate of evaporation from the clay pot. [2]" "- use scale on beaker / tube / ruler / eq
• volume / mass of water lost from beaker / level of water in beaker / distance moved by bubble
• use clock / measure time / stated time
• divide volume / distance by time - CORRECT ANSWER Suggest how the student could measure the rate of evaporation from the clay pot. [3]"

• using ruler / balance / scales
• of both solutions / seedlings complete with minus nitrates - CORRECT ANSWER Explain the measurements that the student could make to determine if nitrate ions are required for plant growth. [2]" "- nucleus from (body) / adult / diploid cell of male dog
• insert (this) nucleus into enucleated / empty egg cell
• electric shock
• mitosis / cell division
• embryo into uterus / womb
• surrogate mother - CORRECT ANSWER Describe the stages used to clone a male dog. [5]" "For
• can produce genetically identical pet / reduced genetic variation
• may have similar appearance / features to pet
• can be cloned before death / may stop owner grieving Against
• expensive
• pet may behave different due to environment / training
• many dogs used / die in attempt / dog farming / unethical
• shorter life span
• idea of reduce variation within breed / inbreeding idea bad for breed health - CORRECT ANSWER Comment on whether cloning pets is a good idea. [4]" "- more energy transferred / less energy lost / less heat loss / less movement in aquatic / more of producer eaten / not all crop eaten - CORRECT ANSWER Suggest why the biomass transfer is different in the coral reef compared to the crop field. [1]" "- uses neurones / nerve cells

• electrical
• goes to target cells only / specific (locus) / eq
• (response) is usually short (term) - CORRECT ANSWER Describe three differences between the nervous system and the hormonal system. [3]" "- increasing (kinetic) energy / molecules move more
• more collisions / more enzyme substrate complexes formed
• above 37°C / 40°C / optimum / eventually / at higher temperature enzyme denatures / change in active site / substrate and enzyme can no longer bind / fit / eq - CORRECT ANSWER Explain the effect that increasing temperature has on the rate of gas production by the yeast. [3]" "- use (collect gas in) measuring cylinder / (gas) syringe / eq
• measure volume / cm³ in time / or time to produce volume / eq - CORRECT ANSWER Describe how the student could measure the rate of gas production in this experiment. [2]" "- the middle value - CORRECT ANSWER State what is meant by the term median. [1]" "- median used as each age has wide / high range / not (influenced by) affected by / any reference to / reduces effect of extreme values / data is skewed / less affected by anomalies - CORRECT ANSWER Give a reason why the median is used rather than the mean. [1]" "- increases (steeply) up to 20-25 years
• levels off / peaks 20-25 years
• decreases (steadily at constant rate) from 20-25 years - CORRECT ANSWER Vital capacity is the maximum volume of air that a person can force out of their lungs in one breath. Describe the relationship between vital capacity and age shown by the graph. [2]" "- (increases) (up to 20 years) as body / size / mass / chest cavity / lungs / muscle increases / grows / develops
• no / little change (from 20) no further growth / stop growing