ORGANISATION #2

Question 1

The human digestive system has two functions:

Answer 1

breaks down complex food substances

provides the very large surface area for maximum absorption of food

Question 2

digestion

Answer 2

Mouth
Begins the digestion of carbohydrates
Stomach
Begins the digestion of protein; small molecules such as alcohol absorbed
Small intestine
Continues the digestion of carbohydrate and protein; begins the digestion of lipids
Small intestine -
Completes the digestion of carbohydrates and proteins into single sugars and amino acids; absorption of single sugars, amino acids and fatty acids and glycerol
Large intestine
Absorption of water; egestion of undigested food

Question 3

lock and key method

Answer 3

the active site- the protein has a complementary shape to the substrate- the molecule that is taking part in the reaction

the substrate collides with the active site of the enzyme and becomes attached
the enzyme then catylyes the breakdown of the substrate- the fit between the active site and the enzyme is perfect
products released from active site
enzyme can be reused

Question 4

Factors affecting enzyme action temp

Answer 4

Temperature
At low temperatures, the number of successful collisions between the enzyme and substrate is reduced because their molecular movement decreases. The reaction is slow.
Higher temperatures break the forces that hold the enzyme together causing the enzyme to denature and the subtrate no longer fits

Question 5

The effect of pH

Answer 5

Enzymes are also sensitive to pH. Changing the pH of its surroundings will also change the shape of the active site of an enzyme.

Question 6

what breaks down carbohydrate

Answer 6

carbohydrase

Question 7

Carbohydrases break down carbohydrates into

Answer 7

simple sugars

Question 8

what breaks doen starch

Answer 8

amylase

Question 9

amylase breaks starch into

Answer 9

glucose

Question 10

what breaks down protein

Answer 10

protease

Question 11

what does protease break the protein into

Answer 11

amino acids

Question 12

what breaks down lipids

Answer 12

lipase

Question 13

what do lipase break down lipids into

Answer 13

fatty acids+ glycerol

Question 14

bile-

Answer 14

Emulsifies lipids, breaking them up physically into tiny droplets. Tiny droplets have a much larger surface area, over which lipases can work, than larger pieces, or drops of lipid.

Question 15

Humans have a double circulatory system. The heart pumps blood through two circuits:

Answer 15

the pulmonary circulation

the systemic circulation

Question 16

what does the pulmonary circuit do

Answer 16

The pulmonary circulation transports blood to the lungs. At the lungs:
oxygen diffuses into the blood from the alveoli - the blood becomes oxygenated
carbon dioxide diffuses from the blood into the lungs
The pulmonary circulation is under lower pressure, because:
blood is delivered to the lungs only, which are very close to the heart
in a healthy person, this lower pressure is optimum for the diffusion of gases

Question 17

what does the systemic circuit do

Answer 17

The systemic circulation transports:
oxygen and nutrients to the body
carbon dioxide and other wastes away from cells
The systemic circulation is under high pressure - it has to deliver blood to the extremities of the body.

Question 18

arteries

Answer 18

Always carry blood away from the heart
Carry oxygenated blood, except for the pulmonary artery
Carry blood under high pressure
Have thick muscular and elastic walls to pump and accommodate blood
A type of supporting tissue called connective tissue provides strength
The channel in the blood vessel that carries blood - the lumen - is narrow
Have a wide lumen

Question 19

veins

Answer 19

Always carry blood to the heart
Always carry deoxygenated blood, except for the pulmonary vein
Carry blood under low or negative pressure
Have thin walls - have less muscular tissue than arteries
Have less connective tissue than arteries
Have a wide lumen

Question 20

capillaries

Answer 20

The walls of capillaries are just one cell thick. Capillaries therefore allow the exchange of molecules between the blood and the body’s cells - molecules can diffuse across their walls. This exchange of molecules is not possible across the walls of other types of blood vessel.

Question 21

whats in the blood

Answer 21

rbc
wbc
platelets
plasma

Question 22

plasma
rbc
wbc
platelets

Answer 22

Plasma
Transporting carbon dioxide, digested food molecules, urea and hormones; distributing heat
Red blood cells
Transporting oxygen
White blood cells
Ingesting pathogens and producing antibodies
Platelets
Involved in blood clotting

Question 23

rbc

Answer 23

They have a biconcave shape - they are the shape of a disc that is curved inwards on both sides - to maximise their surface area for oxygen absorption.
They are thin, so there is only a short distance for the oxygen to diffuse to reach the centre of the cell.

Question 24

wbc

Answer 24

have phagocytes Phagocytes engulf and destroy unwanted microorganisms that enter the blood
have lymphocytes- Lymphocytes produce soluble proteins called antibodies when a foreign body such as a microorganism enters the body.

Question 25

platelets

Answer 25

Platelets stop bleeding in two main ways:
they have proteins on their surface that enable them to stick to breaks in a blood vessel and clump together
they secrete proteins that result in a series of chemical reactions that make blood clot,

Question 26

components of blood

Answer 26

red blood cells
platelets
plasma
antibodies

Question 27

chd

Answer 27

fatty material blocks coronary arteries

If a blockage builds up, the amount of oxygen reaching the heart muscle is reduced.

Question 28

different treatments for heart disease

Answer 28

Drugs - statins
Heart transplant
Replacement heart valves
Stents

Question 29

statins adv and dis

Answer 29

Reduce the risk of heart attack. Used to reduce high cholesterol levels that have genetic causes. May have beneficial effects on other conditions.

Not suitable for people with liver disease. Some side effects. Must be taken for life.

Question 30

heart transplant adv and dis

Answer 30

Improve quality of life.

Few donor hearts are available. Recovery time is long. There is a risk of rejection by the body’s immune system.

Question 31

stents

Answer 31

Widen coronary arteries that have not responded to drug treatment. The recovery time is short following insertion of the stent.

In a minority of cases, further treatment is required.

Question 32

transpiration

Answer 32

When the plant opens its stomata to let in carbon dioxide, water on the surface of the cells of the spongy mesophyll and palisade mesophyll evaporates and diffuses out of the leaf.

Question 33

what affects rate of transpiration

Answer 33

temperature
humidity
air movement
light intensity