B3 AQA

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What is osmosis?
The diffusion of water across a partially permeable membrane
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What does active transport allow?
Cells to take in substances against concentration gradient
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What are sports drinks?
Solutions of sugar and mineral ions
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What does a sport drink do?
Rehydrates cells, replaces mineral ions lost in sweat and the glucose that has been used in respiration
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When are sports drinks useful?
After intense exercise as sweating causes a great loss of ions and water, as well as glucose. Water is as effective as a sports drink during regular exercise
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What is an isotonic solution?
A solution that matches the concentration of the body fluids
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What exchange surface do the lungs contain?
Gaseous exchange surface
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How is the surface area of the lungs increased?
By the alveoli
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What are the properties of the alveoli?
Thin walls, large surface area, good blood supply
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Why are the lungs ventilated?
To maintain a steep diffusion gradient
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Where does the oxygen diffuse into?
The capillaries surrounding the alveoli
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Where does the carbon dioxide diffuse into?
Back into the lungs to be exhaled
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What happens when we breathe in?
The intercostal muscles and diaphragm contract, ribcage move upwards and outwards, diaphragm flattens, volume of thorax increases and pressure in thorax decreases
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What happens when we breathe out?
Intercostal muscles and diaphragm relax, ribcage moves downwards and inwards, diaphragm becomes domed, volume of thorax decreases and pressure increases
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What are villi?
Finger-like projections which greatly increase the surface area for absorption to take place. They line the inner surface of the small intestines and are the exchange surface for food molecules
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Properties of villi?
Thin walls with many capillaries close to the walls
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How are soluble products of digestion absorbed by the villi?
By diffusion or active transport
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What do the stomata do?
Allow carbon dioxide to enter and oxygen and water vapour to leave
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Why are the leaves flat and thin with internal air spaces?
To increase the surface area for diffusion of gases
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How and why is the surface area of the roots increased?
By the root hair cells for the absorption of water and mineral ions
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What happens if water is lost faster than it can be replaced?
The stomata are closed up by the guard cells to prevent wilting/excessive water loss
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How is water lost from the leaves?
Through transpiration/evaporation
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Where does water vapour escape from?
The stomata when they open to allow carbon dioxide to enter
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What does wilting do?
Helps reduce water loss. The leaves hang down and collapse, which reduces surface area
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What does the double circulation system contain?
Blood vessels, blood and the heart
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The aorta carries blood to...
the rest of the body
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The pulmonary artery carries deoxygenated blood to...
the lungs to be oxygenated
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The 4 chambers of the heart are called
The atria and ventricles
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What do the valves do?
Prevent backflow of the blood
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Right atrium receives blood from...
The vena cava
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Left atrium receives blood from...
The pulmonary vein
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Ventricles contract to force blood into...
The pulmonary artery (right ventricle) and aorta (left ventricle)
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The heart muscles is supplied with blood by...
The coronary arteries
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Arteries...
Carry blood away from the heart, have thick walls containing elastic and muscle tissues
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Veins...
Have thinner walls than arteries, often have valves to prevent backflow of blood
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Capillaries...
Are narrow, thin walled (one cell thick) and carry the blood through the organs, allow exchange of substances with all living cells in the body
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How can blocked or narrowed arteries be widened?
Through the use of a stent
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Can heart valves be replaced?
Yes if they are damaged
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Blood plasma transports...
Dissolved food molecules, carbon dioxied, and urea from the liver to the kidneys where urine is made
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Red blood cells are...
biconcave discs that don't have a nucleus. Contains haemoglobin
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Oxygen + Haemoglobin forms...
Oxyhaemoglobin
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White blood cells form...
part of the body's immune system
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Platelets are...
small fragments of cells that help clot blood at site of a wound
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Xylem tissue...
transports water and mineral ions from roots to stem
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Phloem tissue...
carries dissolved sugars from leaves to rest of plant
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Keeping the internal conditions within a narrow range is called...
Homeostasis
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Waste products that have to be removed from the body include...
Carbon dioxide (via lungs) and urea (produced in liver from breakdown of amino acids. removed by kidneys through urine, temporarily stored in bladder)
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A healthy kidney produces urine by...
filtering the blood then reabsorbing all the sugar, then reabsorbing the dissolved ions needed by the body, then reabsorbing as much water as body needs, then urea is released as well as excess ion and water in urine
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When a kidney fails they can be treated by...
dialysis
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Dialysis fluid...
contains the same concentration of useful substances as the patient's blood
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What happens if a kidney transplant takes place?
The dialysis machine will no longer be necessary
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How is the immune system 'suppressed'?
By using immunosuppressant drugs
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Why are they used?
To reduce the risk of the kidney being rejected
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What is the recommended human body temperature?
About 37°C - allows enzymes to work efficiently
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If core temperature rises...
Blood vessels near surface of skin dilate to allow more blood to flow through capillaries. Energy is transferred by radiation and skin cools.
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What happens to the sweat glands when core temp rises?
They produce more sweat. Water in sweat evaporates from skin's surface, the energy required for water to evaporate comes from skin surface so we cool down
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If core temperature falls...
Blood vessels near the surface of skin constrict and less blood flows through skin capillaries. Less energy is radiated
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Why do we shiver?
Because the muscles contract quickly. This requires respiration and some of the energy released warms the blood
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How are glucose levels controlled?
By hormones. The pancreas releases insulin which causes the glucose to move from blood into cells
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What happens in the liver if there is excess glucose?
It is converted into the glycogen to be stored
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What is Type 1 diabetes?
When there is none or too little insulin produced by the pancreas, causing the blood sugar level to be very high
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How is type 1 diabetes controlled?
By injections of insulin
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What does glucagon do?
It causes the glycogen in the liver to change into glucose which is released back into the blood
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What do humans pollute?
The land, air and water
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Air pollution causes...
Acid rain
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Why are forests cut down?
To clear land for farming
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What does deforestation lead to?
Reduced biodiversity and an increase in carbon dioxide in the atmosphere
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Destruction of peat bogs also cause...
an increase in carbon dioxide in the atmosphere
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Where does carbon dioxide naturally occur?
Oceans, rivers, lakes and ponds
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Global warming causes...
Changes in the Earth's climate, rise in sea level, reduced biodiversity, changes in migration patterns and distribution of species
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What are biofuels made from?
Natural products
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What are the two types of biofuel?
Biogas and ethanol-based fuels
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How are ethanol-based fuels produced?
Anaerobic fermentation of sugars from plants. The ethanol is distilled from the fermentation product can be used as fuel
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Biogas is mainly...
Methane. It is made by the anaerobic fermentation of a wide range of substances and plant material containing carbohydrate
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Can it be made on a large or small scale?
Both
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Short food chains...
make food production more efficient as less energy is wasted
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We can produce meat more efficiently by..
Keeping them in warm sheds or preventing it from moving
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Fish stocks can be controlled by...
Fishing quotas and net size
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What does the fungus Fusarium produce?
Mycoproteins. They are produced in aerobic conditions
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How can it be grown?
Fusarium can be grown in an industrial fermenter
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What does the air supply in an industrial fermenter do?
Provides oxygen for respiration
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What do the stirrers or gas bubbles do?
Keep the microorganisms spread out and provide an even temperature
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Why is there a water cooled jacket around the outside?
Respiring microorganisms release energy which heats the contents
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What are the sensors for?
They monitor pH and temperature
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Other cards in this set

Card 2

Front

What does active transport allow?

Back

Cells to take in substances against concentration gradient

Card 3

Front

What are sports drinks?

Back

Preview of the front of card 3

Card 4

Front

What does a sport drink do?

Back

Preview of the front of card 4

Card 5

Front

When are sports drinks useful?

Back

Preview of the front of card 5
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