GCSE Revision 2/7 Flashcards
What do digestive glands do
Produce digestive juices containing enzymes
What does the stomach do
Digests food
What does the liver do
Produces bile
What does the small intestine do
Digests food and absorbs soluble food
What does the large intestine do
Absorbs water from undigested food
How are villi adapted (3)
Large surface area to absorb food molecules (by both diffusion and active transport)
Thin wall for short diffusion path
Good blood supply to carry the food molecules away
Carbohydrates
Made of units of sugar
Glucose- 1 sugar
Sucrose- 2 sugars
Lipids
Three molecules of fatty acids linked to one molecule of glycerol
Proteins
Long chains of amino acids, folded to form a specific shape
Lock and key model (3)
Substrate and enzyme meet
Substrate fits into the active site
Substrate splits into products which leave the active site; enzyme is reused
Metabolism
The sum of all the reactions that take place in a cell/the body
How do digestive enzymes work (3)
They are produced by specialised cells in glands and in the lining of the small intestine
They pass out of the glands into the digestive system
They come into contact with the food so it is digested
What pH are the mouth and small intestine
Alkaline
Amylase (2)
Produced by salivary glands, the pancreas and the small intestine
Catalyses the digestion of starch into sugars in the mouth and small intestine
Protease (2)
Produced by the stomach, the pancreas and the small intestine
Catalyses the breakdown of proteins into amino acids in the stomach and small intestine
Lipase (2)
Produced by the pancreas and the small intestine
Catalyses the breakdown of lipids to fatty acids and glycerol
What does bile do
It neutralises the stomach acid
Makes conditions slightly alkaline
Emulsifies fats (breaks large drops of fat into smaller ones) to increase the SA of the fats for lipase to work on
Where is bile produced
The liver
Where is bile stored
The gall bladder
What is blood and what is it made up of
Blood is a tissue made up of plasma. The plasma contains red blood cells, white blood cells and platelets
What does the blood transport (3)
CO2 from the organs to the lungs (and oxygen the other way)
Soluble products of digestion from the small intestine to other organs
Urea from the liver to the kidneys
Red blood cells (3)
Biconcave
No nucleus
Contain haemoglobin
Haemoglobin + Oxygen
Oxyhaemoglobin
White blood cells (2)
Have a nucleus
Form part of the body’s defense system against microorganisms
In which ways can white blood cells protect the body
Some produce antibodies, some produce antitoxins, and other engulf other microorganisms
Platelets (3)
Small fragments of cells
Do not have a nucleus
Help the blood to clot
How does blood clotting work
Platelets release chemicals that form a mesh of insoluble fibres across the wound
The platelets then stick together to form clumps in the mesh
This barrier stops blood cells
Arteries (3)
Carry blood AWAY from the heart
Have thick walls containing another thick layer of muscle and elastic tissue
Small lumen
Veins (4)
Carry blood TOWARDS the heart
Have thinner walls than arteries
Large lumen
Valves along their length to prevent backflow of blood
Capillaries (4)
One cell thick
Narrow lumen
Carry blood through the organs
Allow the exchange of substances with all the living cells in the body
Heart cycle (beginning in right atrium)
Right atrium - right ventricle - pulmonary artery - lungs - pulmonary vein - left atrium - left ventricle - aorta - rest of the body- vena cava
Coronary artery
The heart muscle is supplied with blood from these arteries, which come just before the aorta
How does coronary heart disease occur
When the coronary arteries become blocked/narrow due to a buildup of fatty material inside them
How does a stent work (3)
It is a metal mesh placed in the artery
A tiny balloon is inflated to open up the blood vessel and the stent
The balloon is removed, but the stent remains
How do statins work
They reduce blood cholesterol levels which slows down the rate at which fatty material is deposited in the coronary arteries
What problems could leaky valves cause
Blood could flow in the wrong direction
How can you counter leaky valves
Replace them with artificial or animal valves
How is your heart rate controlled
Controlled by a group of cells in the right atrium that form a natural pacemaker
What do pacemakers do
Correct irregularities in the heart rhythm
What do artificial hearts do
Keep patients alive while they wait for a transplant
Let their heart rest as an aid for recovery
Breathing in
Ribs move up and out and the diaphragm flattens; volume increases
Increased volume = lower pressure
Atmospheric air at higher pressure than the chest, so air is drawn into the lungs
Breathing out
Ribs fall and the diaphragm moves up; volume decreases
Decreased volume = increased pressure
Pressure in the chest is higher than the outside, so air is forced out of the lungs
How does the ribcage move up and down
The intercostal muscles between the ribs contract (moves up) and relax (moves down)
Epidermal tissue
Covers the plant
Palisade mesophyll
Contains chloroplasts for photosynthesis
Spongy mesophyll
Has many air spaces and large SA for diffusion of gases
Xylem
Phloem
Water and mineral ions from the root to the rest of the plant
Dissolved food from the leaves to the rest of the plant
Translocation
Phloem carrying dissolved sugars from the leaves to the rest of the plant
Transpiration
The loss of water vapour from inside a plant from the surface of its leaves
How does water leave the plant (3)
Water passes through the plant to the cells in the leaves
Water then evaporates from the cells into the air spaces between them
The water then diffuses out of the plant through the open stomata
What conditions is transpiration more rapid (temp, humidity, air flow, light intensity)
Hot, dry, windy and bright conditions
(more KE, steeper concentration gradient, steeper concentration gradient (as water vapour is blown away), more light)
How do plants control water loss (3)
Waxy cuticle on top of the leaf to prevent water loss
Most of the stomata are on the underside of the leaf
Leaves may collapse (wilt), reducing their surface area
Stomata may close (but this also stops photosynthesis)
