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Biology AQA GCSE > Paper 1 > Flashcards

Paper 1 Flashcards

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1
Q

Osmosis definition

A

The diffusion of water through a partially permeable membrane from an area of high water concentration to low water concentration down a concentration gradient

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2
Q

Describe the cell cycle

A

Stage 1: Replicate of DNA to form 2 copies of each chromosome. Increase in sub-cellular structures eg mitochondria.
Stage 2: Mitosis (nucleus divides). One set of chromosomes pulled to each end of the cell
Stage 3: Cytoplasm and cell membrane divide to form 2 identical daughter cells

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3
Q

How many pairs of chromosomes are in normal body cells?

A

23 pairs

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4
Q

Define differentiation

A

The process in which cells become specialised for specific functions

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5
Q

Differentiation in plant v animal cells

A

Animals: specialisation happens early in life

Plants: differentiate throughout life. Undifferentiated cells are formed at meristems, where cell elongation takes place.

Plant cells can also become unspecialised and re-differentiate many times.

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6
Q

Food test for starch

A

Add iodine solution
Colour change from orange to blue black in presence of starch

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7
Q

Food test for sugars

A

Blue Benedict’s solution turns brick red on heating

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8
Q

Food test for protein

A

Add Biuret reagent
Colour change blue to purple

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9
Q

Food test for lipids

A

Add ethanol solution
A white precipitate forms

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10
Q

Metabolism

A

The sum of all reactions in the cell or body

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11
Q

Arteries carry blood…

A

…away from the heart

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12
Q

Veins carry blood…

A

…towards the heart

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13
Q

Adaptations of capillaries

A

-Thin walls: efficient diffusion of oxygen and glucose into cells, and carbon dioxide out

Walls are 1 cell thick

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14
Q

Biological valves v mechanical valves

A

M: made from titanium or other polymer
B: from pigs or cattle (sometimes human)

M: can last throughout life
B: need replacement every 12-15 years

M: need to take medicine to prevent blood clotting
B: no medicine required

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15
Q

Inhalation

A

-Ribs move up and out
-Diaphragm flattens and the volume of the chest increases
-Increased volume means a lower air pressure in the chest
-Atmospherics air pressure is higher than the chest so air is drawn into the lungs

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16
Q

Exhalation

A

-Ribs move down and in
-Diaphragm contracts and the volume of the chest decreases
-Decreased volume means a higher air pressure in the chest
-Atmospherics air pressure is lower than the chest so air is forced out of the lungs

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17
Q

Function of the pulmonary artery

A

Takes deoxygenated blood from the right ventricle of the heart to the lungs

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18
Q

Function of the pulmonary vein

A

Carries oxygenated blood from the lungs to the left atrium of the heart

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19
Q

Compare xylem and phloem

A

Xylem: transports water and mineral salts from the roots up to other parts of the plant. Unidirectional. TRANSPIRATION STREAM. provides water to cells to keep them turgid + for photosynthesis

Phloem: transports sucrose and
amino acids from the leaves and other parts of the plant. Bidirectional. Pores in end walls. TRANSLOCATION. moves dissolved sugars made in photosynthesis to other parts of plant allowing for respiration growth and glucose storage

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20
Q

3 ways that pathogens are spread

A

Air/droplet infection
Water
Direct contact

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21
Q

4 components of the blood

A

Red blood cells
White blood cells
Platelets
Plasma

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22
Q

3 adaptations of a RBC

A

-No nucleus- more area for oxygen transport
-Biconcave shape increases SA:V ratio
-Contains haemoglobin to bind to the oxygen

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23
Q

Substances transported in blood plasma

A

hormones
urea
proteins
CO2

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24
Q

Waxy cuticle

A

Makes the leaf waterproof

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25
Q

Upper epidermis

A

-single layer of cells
-protects against water loss
-transparent to allow light through for photosynthesis

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26
Q

Palisade mesophyll

A

-tightly packed cells to maximise light absorption
-Abundant chloroplasts to absorb light for photosynthesis

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27
Q

Spongy mesophyll

A

-loosely organised with lots of air spaces to allow gases to diffuse quickly
-large SA:V ratio to increase the rate of gas exchange

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28
Q

Guard cells

A

Control the opening and closing of the stomata

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29
Q

How do guard cells open and close?

A

When the plant has plenty of water the guard cells become turgid so the guard cell swells and opens the stomata

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30
Q

Stomata

A

Tiny openings on the undersides of leaves (prevents water loss)
Opens to allow gases to diffuse in and out

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31
Q

Describe the characteristics of a prokaryotic cell

A
  • single-celled
  • single loop of DNA not enclosed in a nucleus
  • Small rings of DNA called plasmids
  • smaller than eukaryotic cells
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32
Q

Function of cell membrane

A

controls the movement of substances in and out of a cell

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33
Q

Function of nucleus

A

contains DNA

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34
Q

Function of mitochondria

A

where respiration takes place and energy is released

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35
Q

Function of ribosomes

A

Where proteinsynthesis occurs

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36
Q

Function of cytoplasm

A

chemical reactions happen
Contains organelles

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37
Q

Function of permanent vacuole

A

Filled with cell sap to help keep the cell turgid.

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38
Q

Function of cell wall

A

Made from cellulose fibres and strengthens the cell and supports the plant.

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39
Q

Function of chloroplast

A

Organelles that contains the green pigment, chlorophyll, which absorbs light energy for photosynthesis. Contains the enzymes needed for photosynthesis.

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40
Q

Differences between a light microscope and an electron microscope

A

Light - living samples can be viewed, relatively cheap, low magnification, low resolution, uses light to form images

Electron - samples cannot be living, expensive, high magnification, high resolution, uses a beam of electrons to form images

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41
Q

Define resolution

A

the ability to distinguish between two separate points

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42
Q

Define magnification

A

the ability to make small objects seem larger

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43
Q

Adaptations of a sperm cell

A
  • tail to swim to ovum and fertilise it
  • lots of mitochondria to release energy from respiration
  • acrosome contains enzymes to break through egg cell
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44
Q

Adaptations of a red blood cell

A
  • no nucleus so more room to carry oxygen
  • haemoglobin that binds to oxugen molecules
  • flat bi-concave disc shape to increase surface area to volume ratio
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45
Q

Adaptations of a muscle cell

A
  • contains protein fibres that contract to make cells shorter
  • contains lots of mitochondria to release energy from respirtion allowing muscles to contract
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46
Q

Adaptations of a nerve cell

A
  • branched dendrites to connect with other neurones/effectors
  • myelin sheath insulates the axon to increase transmission speed of electrical impulses
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47
Q

Adaptations of a root hair cell

A
  • lots of mitochondria to release energy for active transport of mineral ions from soil
  • no chloroplasts as it is underground and photosynthesis cannot take place
    -High SA:V ratio for efficient absorption
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48
Q

Adaptations of a palisade cell

A
  • lots of chloroplasts containing chlorophyll to absorb light energy
  • narrow so that they can be tightly packed together
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49
Q

Define diffusion

A

The spreading out of particles resulting in a net movement from an area of higher concentratio to an area of lower concentration
Down a concentration gradient

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50
Q

Define active transport

A

The net movement of particles from an area of low concentration to an area of higher concentration using energy
Against a concentration gradient

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51
Q

Where is diffusion used

A
  • Humans - nutrients in small intestine diffuse into capillaries through villi. Oxygen diffuses from air in alveoli to blood in capillaries. Urea from cells into blood for excretion
  • Fish - oxygen from water to blood through gills. C02 from blood to water
  • Plants - C02 for photosynthesis diffuses through stomata into leaves. Oxygen diffuses out of leaves through stomata
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52
Q

Where is osmosis used

A
  • Plants - water moves by osmosis from a dilute soltion to a concentrated solution in the root hair cell
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53
Q

Where is active transport used

A
  • Humans - sugar molecules can be absorbed from small intestine into blood
  • Plants - absorbs mineral ions into root hair cells from dilute concentrations in the soil
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54
Q

Factors affecting the rate of diffusion

A
  • Concentration gradient - The greater the difference in concentration, the quicker the rate of diffusion.
  • Temperature - The higher the temperature, the more kinetic energy the particles will have, so they will move and mix more quickly.
  • Surface area of membrane - The greater the surface area, the faster the rate of diffusion.
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55
Q

Explain hypotonic, hypertonic and isotonic solutions

A

Hypotonic -concentration of solutes in solution outside cell is lower than internal concentration

Hypertonic - concentration of solutes in solution outside cell is higher than internal concentration

Isotonic - concentration of solutes in solution outside cell is same as internal concentration

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56
Q

How are villi adaptated for exchanging substances

A
  • network of capillaries for access to ions
  • large surface rea due to folding and microvilli
  • cell wall only one cell thick - reduces the distance that gases need to travel to diffuse, which can lead to faster gas exchange
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57
Q

How are alveoli adapted for exchanging substances

A
  • large surface area
  • moist - gases dissolve in the moisture helping them to pass across the gas exchange surface
  • one cell thick
  • rich blood supply
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58
Q

Advantages and disadvantages of adult stem cells

A

+ fewer ethical issues- adults can consent
+ donors recover quickly
-could have long wait for donor
-can only differentiate into certain types of specialised cells

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59
Q

Advantages and disadvantages of embryonic stem cells

A

+ can form any specialised cell so can treat a wide range of diseases
+ uses spare embryos from fertility clinics
-ethical issues
-relatively under researched
-risk of transferring viral infections to patients

60
Q

Advantages and disadvantages of plant meristem

A

+ rare species of plants can be cloned to prevent extinction
+ plants with desirable traits can be cloned
+ fast and low cost production of large numbers of plants
-genetically identical so whole population is at risk of disease

61
Q

What is therapeutic cloning

A
  • cells from a patients body are used to create a cloned early embryo of themselves
  • stem cells from this embryo can be used for medical treatments and growing new organs
  • these stem cells have the same genes as the patient so are less likely to be rejectd when transplanted
62
Q

Adaptations of veins

A
  • have valves to stop blood flowing wrong way
  • thin walls
  • large lumen
63
Q

Adaptations of arteries

A
  • thick muscular and elastic walls
  • walls can stretch and withstand high pressure
  • small lumen
64
Q

What is the purpose of the gall bladder

A
  • stores bile
    –> bile neutralises hydrochloric acid from stomach and emulsifies fat into small droplets with a large surface area
65
Q

What is the purpose of the liver

A

makes bile

66
Q

What is the purpose of the stomach

A
  • churns food with muscles - mechanical digestion
  • releases protease
  • releases hydrochloric acid which kills pathogens
67
Q

define digestion

A

the process of breaking down large, insoluble food molecules, such as proteins and starch, into smaller, soluble molecules that the body can absorb and use

68
Q

What is a double circulatory system

A

a system where blood passes through the heart twice for each complete circuit of the body
- right ventricle pumps blood to lungs where gas exchange takes place
- left ventricle pumps blood around rest of body

69
Q

Purpose of vena cava

A

brings deoxygenates blood into heart

70
Q

Purpose of aorta

A

carries oxygenated blood around the body

71
Q

Explain lock and key theory

A
  • enzymes active site is a specific shape
  • enzyme will oly catalyse a specific reaction because the substrate is complimentary to active site
  • enzymes can break molecules into smaller ones or bind smaller molecules to form larger ones
  • when products have been released the enzymes acive site can bind to another substrate molecule. Enzyme is unchanged
72
Q

Explain denaturation

A
  • active site’s shape is changed by extreme pH or heat
  • substrate no longer fits into active site
  • They can no longer bind so enzyme cannot catalyse reaction
73
Q

Why is there little/no enzyme activity at low temperatures (sometimes)

A
  • little kinetic energy means low numbers of collisions.
74
Q

Explain amylase

A

produced in salivary glands, pancreas, small intestine
starch

75
Q

Explain protease

A

produced in stomach, pancreas and small intestine
proteins

76
Q

Explain lipase

A

produced in pancreas, small intestine
lipids

77
Q

Factors affecting transpiration

A
  • temperature - higher increases transpiration as water evaporates faster in higher temperatures
  • humidity - lower increases as it means there is a steeper concentration gradient between air and leaf
  • wind speed - higher increases as it removes water vapour quickly maintaining a steep concentration gradient
  • light intensity - higher increases as the stomata opens wider to let more c02 in for photosynthesis as theres more light
78
Q

What is transpiration

A

The constant movement of water up the plant

79
Q

What is translocation

A

The movement of dissolved sugars from leaves to the rest of the plant

80
Q

Describe measles

A
  • spread by inhalation of droplets from infected people sneezing/coughing
  • fever, rash, could be fatal
  • MMR vaccine
81
Q

Describe HIV

A
  • sexual contact and exchange of body fluids
  • flu like symptoms at first - leads to AIDS where immune system cannot fight off infections
82
Q

Describe TMV

A
  • Spread by contact of plant with infected material, soil and animal/plant vectors
  • discolouration where chlorophyll is destroyed reduces ability to photosynthesise
83
Q

How do viruses damage or destroy cells

A

They live and reproduce rapidly inside a =n organisms cells

84
Q

How do bacteria destory or damage cells

A

Reproduce rapidly inside organisms and may produce toxins to damage tissues and cause illness

85
Q

Describe salmonella

A
  • spread by bacteria in or on food being ingested
  • fever, vomiting, diarrhoea
  • poultry can be vaccinated to prevent spread. disinfect surfaces and wash hands w soap and water etc
86
Q

Describe gonorrhoea

A
  • spread by direct sexual contact
  • yellow or green discharge from vagina or penis, pain when urinating
  • barrier contraception, antibiotics
87
Q

Describe rose black spot

A
  • spread by water and wind
  • purple or black spots on leaves that turn yellow and drop, reducing ability to photosynthesise
  • fungicides and removal/destroyal of leaves
88
Q

Describe malaria

A
  • mosquitos feed on blood of infected people and spread the protist when they feed on another person
  • fever. can be fatal
  • prevent vectors from breeding, mosquito net, anti malarial medicine
89
Q

How to control the spread of communicable disease

A
  • Hygeine - hand washing, disinfecting, keeping raw meat separate, covering mouth when coughing/sneezing
  • Isolation of infected party
  • Controlling vectors - limit breeding and controlling population
  • Vaccination - herd immunity
90
Q

How do aphids affect plants

A

Suck mineral ions and glucose from phloem
Prevent glucose from travelling around the plant
Not enough glucose to make proteins for growth

91
Q

How does nitrate deficiency affect plants

A
  • Without nitrates, the amount of
    chlorophyll in leaves reduces
  • This means leaves turn a pale green or yellow colour. This reduces the plant’s ability to photosynthesise and grow properly, which reduces the farmers’ crop yield
  • Farmers or gardeners can add chemical or natural fertilisers, such as manure to increase nitrate levels.
92
Q

How does magnesium ion deficiency affect plants

A
  • Plants use magnesium ions to make chlorophyll in their leaves.
  • The plant is limited in terms of its photosynthetic ability and the plant growth is compromised. Less glucose is made so therefore less proteins are made so less growth can occur
  • Magnesium is a limiting factor in healthy plant growth.
93
Q

Identification of plant pathogens

A
  • gardening manuals or websites
  • laboratory testing of infected plants
  • testing kits containing monoclonal antibodies
94
Q

What are some examples of plant defences

A

PHYSICAL
- thick bark. This is an external layer of dead cells which forms a physical barrier against infection
- Cellulose cell wall
- waxy cuticle
CHEMICAL
- antibacterial chemicals eg witch hazel and mint
- poisons developed in eg stinging nettles to prevent herbivores eating them
MECHANICAL
- Thorns
- Drooping leaves when an insect lands/an animal comes near to prevent being eaten
- mimicry - eg to look as if they have already got eggs on them to prevent insects laying eggs and using their resources

95
Q

What are non-specific defences against pathogens of the human body

A
  • skin is a physical barrier. produces antimicrobial secretions.
  • Cilia and mucus trap particles in air. mucus in nose prevents the movement of pathogens
  • Stomach produces strong acid that destroys ingested pathogens
96
Q

How do white blood cells fight against infection/pathogens

A
  • lymphocytes - antibodies (specific) and antitoxins (bind and neutralise)
  • phagocytes - engulf
97
Q

How do you treat a bacterial infection

A
  • antibiotics
  • risk of antibiotic resistance
98
Q

How to treat a viral infection

A
  • can only use painkillers to treat symptoms
  • drugs that kill viruses often damage the bodys tissues
99
Q

define toxicity, efficacy and dosage

A

Toxicity - how harmful it is
Efficacy - how effective it is
Dosage - how much of the drug is safe and effective to give

100
Q

Describe the process of vaccination

A
  • injecting dead or weakened forms of a pathogen into the body (attenuated)
  • stimulated lymphocytes to produce correct antibodies for that pathogen
  • memory cells are released so that if the same pathogen enters the body again the correct antibodies can quickly be produced to prevent the person becoming diseased
101
Q

Stages of clinical trials

A
  • Pre clinical - drug tested in cells tissues and live animals
  • clinical trials - healthy volunteers receive very low doses to test whether it is safe. If safe, healthy volunteers and patients receive drug
  • Peer review - results will be checked and tested by independant researchers
  • Double blind trials - placebo drug is given to one group of patients. neither patients nor doctor know who has been given placebo to reduce bias
102
Q

Drugs extracted from plants and microorganisms:

A
  • digitalis from foxglove
  • aspirin from willow trees
  • penicilin from penicillium mould
103
Q

Describe the process of making monoclonal antibodies

A
  • Mice are injected to stimulate the production of B lymphocytes
  • Tumour cells are cultured
  • Lymphocyted are fused with tumour cells to form hybridoma cells
  • can divide to make a large number of identical cells called a clone
  • monoclonal antibodies can be produced, collected and purified
104
Q

Uses of monoclonal antibodies for cancer

A
  • Cancer cells have antigens
  • Monoclonal antibodies can be designed to bind specifically with these antigens
  • When injected into a person’s body, the monoclonal antibodies will bind with these cancer cells and clump them together.
  • This makes it easier to identify a
    cancerous tumour, which can then be treated or remove
  • carrying drugs that have been attached to them to the tumour

-encouraging your immune system to attack the cancer cells directly

105
Q

Uses of monoclonal antibodies for pregnancy tests

A
  • Urine is applied to the end of a stick
  • the test stick contains monoclonal antibodies that only bind to HCG attache to dye
  • if HCG is present in urine, the monoclonal antibodies bind to it and cause a line of dye to appear
  • A second line appears in the control zone to show the test is working
106
Q

negative effects of monoclonal antibodies

A
  • have more side effects than researchers anticipatedso are not as widely used as was hoped
107
Q

What is coronary heart disease

A

coronary arteries become narrowed by the build up of layers of fatty material
reduces flow of blood, resulting in less oxygen for the heart muscle which can lead to heart attacks

108
Q

Explain stents

A
  • inserted into blocked coronary arteries to keep them open
    +allows more blood to flow
    +less serious surgery
    -risks from anaesthetic used during surgery
109
Q

Explain statins

A
  • drug that reduces blood cholesteol levels, slowing down deposit of fatty material in arteries
    +effective
    +no need for surgery
    +can prevent CHD from developing
    -have to take for many years as it doesnt cure CHD
    -possible side effects like muscle pain, headaches, sickness
110
Q

Explain heart transplants

A
  • artificial hearts can be used to keep patients who are waiting for a donor alive
    +long term cure for serious heart conditions
    +treats problems that cannot be treated in other ways
    -risk of rejection
    -lengthy process
    -major surgery, risk of infection and blood loss
    -risks from anaesthetics used
111
Q

What is health

A

the state of physical and mental well-being

112
Q

What is a risk factor

A

any aspect of yor lifestyle or substance in your body that can increase the risk of a disease developing

113
Q

Diseases as a result of diet risk factor

A
  • Type 2 diabetes - body doesnt respond properly to production of insulin so blood glucose levels cannot be controlled
  • Cardiovascular disease - increased blood cholesterol can lead to CHD
114
Q

Diseases as a result of alcohol risk factor

A
  • liver cirrhosis - tissue becomes scarred meaning liver cannot remove toxins from body or provide sufficient bile
  • fetal alcohol syndrome - alcohol can pass through the placenta, risking miscarriages, premature births and birth defects
115
Q

Diseases as a result of smoking risk factor

A
  • lung disease - cigarettes contain tar carcinogen
  • shrivelled alveoli cannot properly inflate
116
Q

What is a benign tumour

A

Grows slowly; usually grow within a membrane, so can easily be removed; does not invade other parts of the body

117
Q

What is a malignant tumour

A

Grows quickly; invades neighbouring tissues and can spread to other parts of the body in the bloodstream; as the tumour grows, cancer cells detach and can form secondary tumours in other parts of the body - this is called metastasis.

118
Q

What causes cancer

A

Carcinogens cause cancer by damaging
DNA. Carcinogens cause mutations to occur. A single mutation will not cause cancer – several are required

119
Q

What causes a tumour

A

rapid division of abnormal cells
- the tumour secretes chemicals
- the chemicals stimulate the blood vessels to grow. they grow around the tumour
- cancer cells detach from tumour and are transported into blood
- malignant cell gets through capillary wall
- cell divides and a secondary tumour starts to grow

120
Q

Why are cancer cells dangerous

A

Cancer cells are undifferentiated – they do not carry out their normal function.
They divide rapidly

121
Q

What is photosynthesis

A

a chemical reaction in which energy is transferred from environment as light from the sun to leaves of a plant

122
Q

What are the limiting factors of photosynthesis

A

temperature
light intensity
carbon dioxide concentration
amount of chlorophyll

123
Q

how does temperature limit photosynthesis

A
  • low temp = low photosynthesis rate as reactant molecules have less energy
  • high temp means denatured enzymes
124
Q

How does carbon dioxide concentration limit photosynthesis

A
  • used up in photosynthesis so increasing c02 increases rate of photosynthesis
  • at some point another factor becomes limiting
  • carbon dioxide is often the limiting factor for photosynthesis
125
Q

How does light intensity limit photosynthesis

A
  • light intensity is needed so increases rate of photosynthesis
  • at some point another factor becomes limiting
  • photosynthesis will stop if there is little to no light
126
Q

What is the inverse square law

A

light intensity (is proportional to) 1/distance^2

127
Q

What is glucose produced in photosynthesis used for

A
  • converted into insoluble starch for storage (in leaves, bulbs, tubers)
  • produce fat or oil (lipids) for storage
  • produce amino acids for protein synthesis (also need nitrate ions from soil)
  • produce cellulose to strengthen cell walls
  • for respiration to release energy

Plants can’t store glucose as it is because it’s soluble and can draw in water through osmosis

128
Q

How are greenhouses made economical

A

control limiting factors to get highest possible rates of photosynthesis for a low cost to keep profits high

Glass – greenhouses are made of glass in order to trap the sun’s heat, via the greenhouse effect, in the summer to increase the speed of photosynthesis.

Blinds – they have blinds that are used if it is too hot to stop the denaturing of enzymes.

Heaters – during the cold months, farmer use heaters inside the greenhouse in order to artificially provide heat to keep photosynthesising year round.

129
Q

What is respiration

A

exothermic reaction that occurs continuously in the mitochondria of living cells to supply cells with energy

130
Q

What is the energy released from respiration needed for

A
  • chemical reactions to build larger molecules (eg proteins from amino acids)
  • breaking down larger molecules to smaller molecules
  • muscle contraction
  • keeping warm
131
Q

Differences between aerobic and anaerobic respiration

A
  • aerobic - complete oxidation of glucose so large amounts of energy is released. requires oxygen
  • anaerobic - less energy. lactic acid produced.
132
Q

Word equation for fermentation

A

glucose -> ethanol + carbon dioxide
anaerobic respiration in yeast cells
products important for bread and alcohol

133
Q

Word equation for anaerobic respiration

A

glucose -> lactic acid

134
Q

symbol equation for anaerobic respiration

A

C6H12O6 -> 2C3H6O3

135
Q

Symbol equation for aerobic respiration

A

C6H12O6 + 6O2 -> 6CO2 + 6H2O

136
Q

What is the definition of metabolism

A

the sum of all reactions in a cell or the body
- uses the energy released by respiration in cells

137
Q

What are some metabolic processes

A

Carbohydrates - synthesis of carbs from sugars. breakdown of glucose in respiration to release energy

Proteins - synthesis of amino acids from glucose and nitrate ions. amino acids used to form proteins. excess proteins broken down to form urea for excretion

Lipids - synthesis of lipids from one molecule of glycerol and 3 molecules of fatty acid

138
Q

What is oxygen debt

A

the amount of oxygen needed to react with lactic acid to remove it from cells after anaerobic respiration

139
Q

How to remove lactic acid

A
  • lactic acid in muscles
  • transported to liver in blood
  • lactic acid converted to glucose
140
Q

What is the human response to exercise

A
  • heart rate increase
  • breathing rate increases
  • breath volume increases
    all to supply muscles with more oxygenated blood
    if insufficient oxygen is supplied anaerobic respiration takes place leading to build up of lactic acid
    This means muscles will become fatigued and cramp/stop contracting efficiently
141
Q

During long periods of exercise:

A
  • lactic acid levels build up
  • glycogen reserves in the muscles become low as more glucose is used for respiration, and additional glucose is transported from the liver.
142
Q

Explain the effect of a partly blocked coronary artery on the human body [6 marks]

A
  • reduced blood flow to heart
  • less oxygen to heart
  • less glucose to heart
  • less aerobic respiration
  • more anaerobic respiration
  • less energy released
  • less muscle contraction
  • less blood/glucose/oxygen around the body
  • breathlessness
  • tiredness
  • production of lactic acid
  • causes muscle fatigue
143
Q

Explain why scientists use 37c for incubation of bacteria but students use 25c [3 marks]

A
  • 37c is human body temperature
  • bacteria grows best at 37c (salmonella)
  • 25c reduces/prevents the growth of bacteria that are harmful to humans
144
Q

Compare the use of meat-free burgers and meat burgers [6 marks]

A
  • Meat burgers contain more protein for growth
  • Meat-free burgers contain more fibre which aids digestion
  • Meat burgers contain more cholesterol/fat which can lead to CHD/narrowing of the arteries - may need to take statins, may need a stent. Can lead to obesity which is a risk factor for diabetes.
  • meat burgers require animals to be farmed increase in methane in atmosphere - methane contributes to global warming + ethical issues
  • some people won’t eat meat-free burgers some people don’t like the idea of eating fungus some people prefer the taste of meat
145
Q

Explain why the metabolic rate of organism D is greater than the metabolic rate of
organism E. [4 marks]
(D has larger SA:V ratio)

A
  • D has a larger surface area to
    volume ratio and so will lose
    heat more quickly (per unit
    volume 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)
146
Q

Explain why organism D requires a respiratory system, but organism B does not
require a respiratory system. [2 marks]
(D has smaller SA:V ratio than B)

A
  • D has a smaller surface area to
    volume ratio (than B)
  • (so) diffusion distance is too
    large (to meet demands of cells
    / organism)
147
Q

How to find solution that has the same concentration of ions/water in it as the specimen inside it (potato in sugar solution eg) [3 marks]

A
  • use five (or more) different
    concentrations of salt / sugar
    solution (in beakers)
  • (by) plotting percentage change
    (in mass / volume) on / using a
    graph
  • determine the concentration
    where the curve / line crosses
    the zero percentage change (in
    mass / volume)

Biology AQA GCSE (2 decks)

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