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GCSE BIOLOGY > P1 exam questions > Flashcards

P1 exam questions Flashcards

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1
Q

Why did the student dry the surface of each potato piece with a paper towel? (1 mark)

A

To make sure ONLY the potato mass was measured

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2
Q

Explain why the potato pieces in the 0.4 mol/dm3 salt solution decreased in mass? (3 marks)

A

-Water moves out of potato
-by osmosis
-because the solution in the potato is less
concentrated than outside

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3
Q

Explain why a tree might die if the roots of the tree are damaged? (6 marks)

A

Less absorption of water:
-less water so lower rate of photosynthesis
-so less glucose produced for respiration
-so less cellulose produced so fewer cells walls
-so fewer amino acids to make new proteins
-cells lose turgidity

Less absorption of ions / minerals:
-less nitrates so fewer proteins made for growth
-less magnesium ions so less chlorophyll produced
-so lower rate of photosynthesis

Damage to xylem:
-less water transported (to cells)
-fewer nitrates reach cells
-so fewer proteins made for growth
-fewer magnesium ions reach cells
-so less chlorophyll produced
-less magnesium/chlorophyll so lower rate of
photosynthesis

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4
Q

Describe how mitosis produces two genetically identical daughter cells? (4 marks)

A

-DNA is replicated
-the (replicated) chromosomes are pulled to the poles
-cytoplasm and cell membrane divides into two
-the set of chromosomes in each
new cell are identical (two genetically identical daughter cells)

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5
Q

Explain how the changes in the mean width of the stomata in normal conditions are an advantage to the plant? (4 marks)

A

-Stomata closed at night because there is no light for photosynthesis
-This reduces water loss
-Stomata opens wide at midday as maximum light intensity for photosynthesis
-Stomata opens wide to take in more carbon dioxide for photosynthesis

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6
Q

Explain why organism D requires a respiratory system but organism B does not? (2 marks)

A

-D has a smaller surface area to volume ratio than B
-so diffusion distance is too large to meet demands of cells

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7
Q

Explain why the metabolic rate of organism D is greater than the metabolic rate of organism E? (4 marks)

A

-D has a larger surface area to volume ratio and so will lose heat more quickly than E
-D requires greater rate of respiration
-as respiration is a large part of metabolism
-so need to generate more heat
to keep itself warm

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8
Q

Describe how the alveoli and villi are adapted to increase absorption? (4 marks)

A

> Both have a large surface area:
-to maximise diffusion
Both have thin walls:
-to reduce diffusion distance
Both have a good blood supply:
-to maintain concentration gradient
Villi have microvilli:
-to further increase surface area
Cells of villi contain many mitochondria:
-for active transport

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9
Q

Suggest one reason for the change in the number of new HIV cases between 2014 and 2018? (1 mark)

A

-Better education
-Better drugs
-Condoms more widely used

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10
Q

Explain how a vaccine for HIV could work to prevent a person developing HIV infection? (4 marks)

A

-inactive/weakened HIV is injected into body
-WBCs produce antibodies against inactive
virus
-if infected with HIV, specific antibodies are produced quickly
-antibodies destroy the active HIV

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11
Q

Describe how the monoclonal antibody for HIV can be produced? (4 marks)

A

-HIV antigen injected into mouse
-extract lymphocytes that make a specific antibody to HIV antigen
-lymphocytes combined with a tumour cell to create a hybridoma
-hybridoma cloned to create many cells that produce the antibody

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12
Q

Suggest how the monoclonal antibody for HIV helps to prevent a person infected with HIV developing AIDS? (3 marks)

A

-Monoclonal antibody is specific to HIV antigen
-Monoclonal antibodies attach to HIV antigens
-so HIV cannot bind to human cell

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13
Q

Suggest 2 factors that affect the rate of diffusion of oxygen in a jellyfish? (2 marks)

A

-Temperature
-Concentration gradient

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14
Q

Explain how the human breathing system is adapted to maximise the rate of gas exchange? (6 makrs)

A

Large number of alveoli:
-Large surface area to maximise diffusion

Alveoli have thin walls:
-To reduce diffusion distance

Good blood supply:
-To maintain concentration gradient
-To remove oxygen quickly

Capillaries have thin walls/ one cell thick:
-To reduce diffusion distance

Lungs are ventilated:
-To bring in oxygen and remove carbon dioxide
-To maintain concentration gradient

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15
Q

Name one type of cell in a potato plant that does not contain chloroplasts? (1 mark)

A

Root hair cell

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16
Q

What is the name of the part where your eye looks through in a microscope? (1 mark)

A

Eyepiece

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17
Q

Compare the structure of a red blood cell with a plant cell? (6 marks)

A

Differences:
-RBC has no nucleus but a plant cell does
-RBC has no cell wall but a plant cell does
-RBC contains haemoglobin, plant does not
-RBC doesn’t contain any chloroplasts
-RBC is a biconcave disc
-RBC are much smaller than plant cells

Similarities:
-Both has a cytoplasm
-Both have a cell membrane
-Both have pigments

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18
Q

Explain why a red blood cell bursts in water but a plant cell does not? (2 marks)

A

-Water enters the cells by osmosis
-Plant cell has cell wall to prevent it from bursting but RBC does not

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19
Q

Explain how a transplant of bone marrow cells can help to treat medical conditions? (2 marks)

A

-Bone marrow cells differentiate into many types of cells
-So will cure diseases where cells are damaged

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20
Q

Describe how one feature of an axolotl’s gills increases the rate of diffusion of oxygen? (2 marks)

A

-Large surface area of gills
-To access lots of water

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21
Q

Explain why having only one ventricle makes the circulatory system less efficient than having two ventricles? (2 marks)

A

-Oxygenated and deoxygenated blood mixes
-So less oxygen reaches the body

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22
Q

Explain why an axolotl may die in water with a low concentration of oxygen? (4 marks)

A

-Concentration gradient of oxygen is less steep
-So less oxygen diffuses into blood/cells
-So less respiration occurs so less energy is released
-So less metabolism

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23
Q

Name one condition that could be treated using regenerated human tissue? (1 mark)

A

-Diabetes
-Paralysis

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24
Q

Suggest why a large surface area to volume ratio is an advantage to an earthworm? (1 mark)

A

-Earthworm absorbs more energy
-Increases gas exchange

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25
Why could a blockage inside arteries cause cells in the heart to die? (2 marks)
-Less blood flows to the heart -Less oxygen reaches the heart muscle
26
Evaluate the use of anti-clotting drugs in patients who have had a stent fitted? (4 marks)
Advantages: -Only take one tablet a day -Only a tablet so easy to take -Effective so less likely to get a blood clot -Drugs are cheap so less cost for NHS -Drugs used for a long time so they're trusted Disadvantages: -Make sure you always have a supply of drugs -Could forget to take drugs -Could still get a blood clot in the first week -Restrictions on lifestyle because you have to get a blood test every few weeks and a restricted diet -Risks associated with puncturing skin -Higher risk of bleeding and bruising
27
Explain why someone's breathing rate increases when they are running? (2 marks)
-To get more oxygen into the blood -For use in respiration/ releasing energy for muscle contraction
28
Name two health conditions that might develop if a person eats a diet high in saturated fats? (2 marks)
Any of: -Coronary heart disease -Stroke -Heart attack
29
What is the smaller molecule that amylase is a polymer of? (1 mark)
Amino acids
30
Name three parts of the human digestive system that produce amylase? (3 marks)
-Salivary glands -Small intestine -Pancreas
31
Explain how amylase breaks down starch in terms of the 'lock and key theory'? (3 marks)
-Starch binds to the active site of the enzyme -Because shape of active site and substrate are complementary -Bonds between the starch molecules are broken to produce smaller molecules
32
Compare the structure and function of xylem and phloem tissue? (6 marks)
Structure: -X made of dead cells/ P made of living cells -P have pores in end walls/ X don't have pores -X is hollow/ P contains cytoplasm -X contains lignin/ P does not -Both made of cells -Both tubular Function: -X transports water/mineral ions/ P transports sugar -X involved in transpiration/ P involved in translocation -X transports unidirectionally/ P transports bidirectionally -Both transport liquids throughout stem/ roots
33
Explain how a very low number of blood components in the body can cause tiredness, frequent infections and bleeding that won't stop after the skin is cut? (6 marks)
Tiredness: -Fewer RBCs -So less haemoglobin -So less oxygen transported around body -So less aerobic respiration -Less energy released for metabolic processes -So organs cannot function as well -So more anaerobic respiration -Lactic acid produced causing muscle fatigue Frequent infections: -Fewer WBCs -So fewer antibodies produced -So fewer pathogens killed Bleeding: -Fewer platelets -So blood does not clot as easily
34
Explain why a person with a tumour blocking the tube leading from the gall bladder to the small intestine would have difficulty digesting fat? (5 marks)
-Less bile reaches the small intestine -Less emulsification of fat -So smaller surface area for lipase to break down fats -pH of small intestine is not neutralised/alkaline -So lipase is not at its optimum pH to break down fat
35
Explain the lock and key theory of enzyme action? (3 marks)
-Enzyme binds to the substrate because they are complementary shapes -So substrate is broken down into products -So products are released and enzymes are not changed
36
Explain why a leaf left in a cupboard with no light for two days did contain glucose but didn't contain starch? (3 marks)
-Starch stores have been converted to glucose -So the glucose can be used for respiration -Because there is no light to make new glucose by photosynthesis
37
Suggest two factors (not age or gender) that would need to be controlled when analysing the effects of consuming alcohol on liver disease? (2 marks)
Any of: -BMI -Smoking habits -Diet -Medication -Ethnicity -Fitness levels
38
Describe the effects of liver failure on the human body? (4 marks)
No bile made: -Fats aren't emulsified -Surface area of fats not increased -pH of small intestine won't be alkaline -Enzymes won't work effectively -Food not digested -May lose weight Lactic acid not broken down: -Accumulation of lactic acid in blood -Lactic acid is toxic -Oxygen debt higher -So muscle pain/fatigue Proteins not broken down in the liver: -Amino acids not deaminated -Amino acids not made into urea -Accumulation of amino acids in the body
39
Suggest one reason why a patient may choose a biological valve over a mechanical valve? (1 mark)
No need to take anticlotting medication
40
Describe the transport of water through a plant from the roots to the atmosphere? (3 marks)
-Water is transported in the xylem -Water evaporates from the leaves -Through the stomata
41
Explain why a person with a leaking heart valve has difficulty exercising? (6 marks)
-Back flow of blood occurs -Less blood pumped around the body -Less oxygen supplied to the muscles -Less aerobic respiration -Less energy released -Less efficient muscle contraction -Anaerobic respiration takes place -Less removal of lactic acid -Lactic acid causes muscle fatigue -Less efficient removal of carbon dioxide
42
Evaluate the use of mechanical and biological replacement heart valves? (6 marks)
Mechanical: -More durable -Blood clots more likely -Have to take anti-clotting medication -If medication not taken, leads to blood clots -Medication can lead to excessive bleeding -Some can hear it open and close -Survival rate at 5 years is slightly higher -Lower % deaths due to heart related problems Biological: -No additional medication required -Ethical issues -Valve may harden More likely to need further operation -More likely to be rejected -More likely to need immuno-suppressant drugs -Both readily available -Little wait time
43
Explain two possible reasons (not nitrate deficiency) for yellow leaves and stunted growth on a plant? (5 marks)
-Reason 1: Plant infected by a pathogen (TMV) -Explanation 1: Causes leaves discolouration so less photosynthesis -Reason 2: Lack of magnesium ions -Explanation 2: Not enough chlorophyll for photosynthesis so not enough glucose to make proteins for growth
44
Suggest how nodules on the roots of a plant benefit the bacteria? (2 marks)
-Bacteria obtain glucose from the plant -Glucose used for respiration
45
Explain how nodules benefit the gorse plant? (2 marks)
-Gorse plants obtain nitrate ions -Needed for amino acids/proteins
46
Describe how monoclonal antibodies and a fluorescent dye could be used to see any Candida albicans pathogens on the slide? (3 marks)
-Bind fluorescent dye to monoclonal antibodies Put fluorescent monoclonal antibodies onto the slide -Monoclonal antibodies will bind to Candida albicans
47
Explain how increased phagocytosis of the Candida albicans pathogen will help the patient? (2 marks)
-More Candida albicans will be engulfed/killed by phagocytes -Therefore less damage to cells/tissues/organs
48
Describe how clinical trials should be carried out? (6 marks)
First to healthy volunteers: -At very low dose -To test for safety/toxicity/side effects Patients with the disease: -Test for optimum dose -Check for side effects -Test for efficacy -Double blind trial -Neither know who has real and who has placebo
49
Describe how the human body: -prevents pathogens from entering -defends itself against pathogens inside the body (6 marks)
Entering: >Skin- -Tough outer layer -Skin acts as a barrier -Scabs form over cuts as a barrier >Stomach- -Contains HCl -To kill bacteria -In food or in swallowed mucus >Eyes- -Produce tears -Containing enzymes that kill bacteria -Tears are antiseptic >Breathing system: -Trachea produces mucus -Mucus is sticky and traps bacteria Defending: -WBCs engulf pathogens -Antitoxins produced to neutralise toxins -Antibodies produced to destroy pathogens -Memory cells formed to give rapid reponse
50
Explain how pancreatic cancer may cause a person to lose weight? (4 marks)
-Reduced enzyme production from pancreas -Food isn't broken down fully -Less glucose absorbed/passed into bloodstream -Less glucose available for respiration so more body fat used up in metabolism
51
Explain how the monoclonal antibody works to treat pancreatic cancer? (3 marks)
-Monoclonal antibody is attached to radioactive substance -Monoclonal antibodies will only attach to the antigen on the cancer cells -So radioactive substance will bind to cancer cells and stop them growing
52
Explain one way the removal of dissolved sugars from the stem of the plant causes stunted growth? (2 marks)
-Less glucose for respiration -So less energy released
53
Suggest how the production of oil on the surface of a leaf may protect a plant from aphids? (1 mark)
The oil may kill the aphid
54
Explain how a deficiency of magnesium causes yellow leaves and stunted growth? (5 marks)
-Yellow leaves due to lack of chlorophyll -So less light absorbed by chlorophyll -So lower rate of photosynthesis -So plant makes less glucose -So plant converts less glucose into protein for growth
55
Describe how a scientist would use a protein to produce the PVY monoclonal antibody? (4 marks)
-Inject the protein into a mouse -Combine lymphoctyes with tumour cells to make hybridoma cells -Find a hybridoma which makes a monoclonal antibody specific to PVY -Scientist clones hybridoma to produce many cells to make the antibody
56
Explain why animals avoid eating the hornet moth? (2 marks)
-It looks like the hornet -So animals avoid the risk of being stung
57
Give two uses of the energy released in respiration? (2 marks)
-Keeping warm -Movement/muscle coordination
58
Describe how energy for the photosynthesis reaction is gained by plants? (2 marks)
-Light -Light is captured/ absorbed by chlorophyll
59
Suggest why a layer of oil stops yeast respiring aerobically? (1 mark)
Stops any oxygen getting in
60
Explain why exercise cannot be sustained when anaerobic respiration takes place in muscle cells? (2 marks)
-Muscles become fatigued and stop contracting -Because not enough energy is transferred
61
Give one use of fermentation in the food industry? (1 mark)
Bread making
62
Describe how glucose from the small intestine is moved to a muscle cell? (2 marks)
-Glucose is absorbed by diffusion into the bloodstream -Then blood delivers glucose to muscles in capillaries
63
Compare anaerobic respiration in yeast cells with anaerobic respiration in muscle cells? (3 marks)
-Yeast produces ethanol but muscles produce lactic acid -Yeast produces carbon dioxide but muscles do not -Both release small amounts of energy
64
What is the purpose of a control? (1 mark)
For comparison/to compare
65
Explain how diabetes can cause the body cells to lose more water? (3 marks)
-Blood is more concentrated -Water moves out of cells by osmosis -Water moves through a partially permeable membrane
66
Define the term double circulatory system? (1 mark)
Blood is pumped to the lungs by the right side of the heart and pumped to the body by the left side of the heart
67
What is an enzyme? (2 marks)
-A protein -Speeds up reactions in living organisms
68
Explain why muscle cells need a large amount of mitochondria? (2 marks)
-Energy is required for contraction -Mitochondria is the site of respiration which releases energy
69
Give 4 changes in the body that help increase the amount of oxygen delivered to working muscles during exercise? (4 marks) (Don't refer to the heart)
-Increased breathing rate -Increased depth of breading (deeper breaths) -Vasodilation -Blood diverted away from other organs
70
What are microvilli and what is their purpose? (2 marks)
-Folds of the cell membrane -Increases the surface area
71
What are cilia? Where can they be found? (2 marks)
-Hair like structures on the surface of cells -Found in the airways- trachea/bronchi
72
Compare the processes of anaerobic respiration in plant cells and muscle cells? (4 marks)
-Neither use oxygen -Both releases a smaller amount of energy -Muscle cells produce lactic acid whilst plant cells produce ethanol -Plant cells produce carbon dioxide whilst muscle cells don't
73
Plants need nitrate ions in order to make proteins. A plant is growing in soil flooded with water. Explain why the plant cannot absorb enough nitrate ions? (5 marks)
-Nitrate ions are absorbed by active transport -They are moved from a lower concentration in the soil to higher concentration in the root hair cell -This requires energy -Energy comes from respiration and respiration requires oxygen -Very little oxygen in flooded soil
74
A student investigated the rate of photosynthesis in leaves. Explain why the leaf discs were placed in sodium hydrogen carbonate solution? (2 marks)
-It provides/ releases carbon dioxide -Carbon dioxide is a reactant in photosynthesis
75
A student investigated the rate of photosynthesis in leaves. Explain why the leaf discs moved to the surface during the investigation? (2 marks)
-Photosynthesis produces oxygen -Bubbles of oxygen will be trapped under the leaf discs causing the discs to float
76
Explain 2 effects of anaerobic respiration on a person's body? (4 marks)
-Muscle fatigue/oxygen debt -Anaerobic respiration produces lactic acid -Increased breathing rate -To provide oxygen to break down the lactic acid
77
Students in schools incubate at 25 degrees. Scientists incubate bacteria at 37 degrees. Explain why? (3 marks)
-37 degrees is human body temperature -Bacteria grow faster at 37 degrees -25 degrees means that pathogens harmful to humans are less likely to replicate
78
Give 2 reasons why it is important to test drugs in clinical trials? (2 marks)
-To check for toxicity -To check for efficacy -To check what the optimum dose is
79
Describe the 3 stages of the cell cycle? (5 marks)
Stage 1 - Cell grows -DNA replicates -Mitochondria increase in number Stage 2 -One set of chromosomes pulled to the poles of the cells -Nucleus divides Stage 3 -Cell membrane and cytoplasm divides -Two genetically identical daughter cells produced
80
Describe the structures and functions in a leaf and the functions of the tissues? (6 marks)
1) Waxy cuticle -Waterproof -Reduces water loss 2) Upper epidermis -Contains no chloroplast -Transparent to allow light to pass through 3) Palisade mesophyll -Packed full of chloroplast for more photosynthesis 4) Spongy mesophyll -Many air spaces -To allow for rapid diffusion of gases 5) Stomata -Open to allow for gas exchange
81
There is a glass jar with glass tubing, balloons, rubber sheet and a rubber bung. This model does not represent the human breathing system well. Give 2 reasons why? (2 marks)
-Alveoli aren't represented -Bronchioles aren't represented
82
Describe how water is transported from the soil to the atmosphere through a plant? (4 marks)
-Water moves by osmosis -Into the root hair cells -Water moves up the xylem from roots to the leaves -Water evaporates out via the stomata -Driven by transpiration
83
Describe 2 aseptic techniques a student could use? (2 marks)
-Secure lid of petri dish with adhesive tape -Sterilise equipment of surfaces before use
84
Explain why the concentration of CO2 in the tube stayed the same between day 0 and 5 in the test tube with the pondweed and tube? (2 marks)
-Pondweed takes in CO2 for photosynthesis -Snail and pondweed are respiring producing CO2
85
Suggest why the concentration of CO2 increased between day 5 and 10 in the pondweed and snail test tube when covered with black paper? (2 marks)
-No light so no photosynthesis -Snail and plant are respiring and so are releasing CO2
86
Explain why the death of the snail caused the concentration of carbon dioxide to increase in the pondweed and snail test tube? (3 marks)
-Snail is being decayed -By decomposers in the pond water -Therefore respiration of the decomposers releases CO2
87
Why did the student leave the starch and amylase solution for 5 minutes before mixing them in the enzyme practical? (1 mark)
So that both solutions could reach the same temperature as the water
88
Explain why the iodine solution did not turn yellow-brown at 5 degrees and 80 degrees? (5 marks)
-Iodine is not yellow brown because starch is still present -At 5 degrees, amylase molecules have low kinetic energy -Therefore there are fewer enzyme substrate collisions -At 80 degrees, amylase has been denatured -So starch can no longer fit
89
The rate of water loss at midnight was much lower than at 12:00. Explain why? (2 marks)
-Stomata are closed -Because there's less/no light
90
Why is it dangerous for a patient with blood group A to receive RBCs from a donor with blood group B? (3 marks)
-Anti-B antibodies in patients will bind to type B antigens on a person's red blood cells -Red blood cells clump together and block capillaries -Cells have a reduced supply of oxygen -So cells can't respire

GCSE BIOLOGY (11 decks)

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