Organisation

Question 1

what do glands do ?

Answer 1

produce digestive juices

Question 2

what does the small intestine do ?

Answer 2

digests food and absorbs food molecules

Question 3

what does the liver do ?

Answer 3

produces bile

Question 4

what does the stomach do ?

Answer 4

digests food

Question 5

what does the large intestine do ?

Answer 5

absorbs water molecules from the remaining undigested food

Question 6

what is an organism ?

Answer 6

the highest level of organisation in a multicellular organism

Question 7

what is an organelle ?

Answer 7

Organelle A specialised unit within a cell which performs a specific function

Question 8

what is a cell ?

Answer 8

Cell The basic building block of all living organisms

Question 9

what is a tissue ?

Answer 9

Tissue A group of cells working together to perform a shared function, and often with similar structure

Question 10

what is an organ ?

Answer 10

Organ A structure made up of groups of different tissues, working together to perform specific functions

Question 11

what is an organ system ?

Answer 11

Organ system A group of organs with related functions, working together to perform certain functions within the body

Question 12

Surface area effect on gas exchange

Answer 12

The size of their surface, or surface area, defines how quickly they can absorb substances. The size of their volume defines how much of these substances they need.

Question 13

Name two blood supply adaptations

Answer 13

the network of blood capillaries that surrounds each alveolus in the lungs
the network of blood capillaries in each villus in the small intestine

Question 14

Effective gas exchange in lungs

Answer 14

The moving blood and ventilated surfaces mean that a steep concentration gradient can be maintained. This increases effective exchange.

Question 15

The human lungs provide an exchange surface adapted for:

Answer 15

absorbing oxygen – needed for respiration – into the blood from the air

transferring carbon dioxide – produced by respiration – from the blood into the lungs then the air

Question 16

The structure of the respiratory system

Answer 16

The human respiratory system is adapted to allow air to pass in and out of the body, and for efficient gas exchange to happen.

The lungs are enclosed in the thorax, surrounded and protected by 12 pairs of ribs. The ribs are moved by two sets of intercostal muscles. There is a muscular diaphragm below the lungs. The lungs are sealed within two airtight pleural membranes. These wrap around the lungs and line the rib cage.

The trachea, or windpipe, branches into two bronchi – one bronchus to each lung. Rings of cartilage in the walls of the trachea help to keep it open as air is drawn in.

The bronchi split into smaller branches and then into smaller tubes called bronchioles. Each bronchiole ends in a cluster of microscopic air sacs called alveoli.

Question 17

The alveoli are adapted to provide a very large surface area for gaseous exchange:

Answer 17

There is also a short diffusion path - the walls of blood capillaries and alveoli are just one cell thick.

The ventilation of the lungs and the blood flow through the surrounding capillaries mean gases are being removed continually, and steep concentration gradients are set up for gases to diffuse.

Question 18

Carbohydrates

Answer 18

Source of energy, glucose is the main respiratory substrate

Starch: potatoes, rice and wheat products, bread, cereals and pasta.

Sugars: fruit, smoothies, fizzy drinks, chocolate and sweets

Question 19

Proteins

Answer 19

Proteins

Growth and repair

Meat, eggs, cheese, beans, nuts and seeds

Question 20

Lipids

Answer 20

Lipids

Energy, make up part of cell membranes so essential for normal growth

Butter and margarine, meat and processed meat, plant oils, oily fish, nuts and seeds

Question 21

Once absorbed by the body, glucose molecules are transported to cells and:

Answer 21

used for respiration

reassembled into the storage form of carbohydrate in animals - glycogen

Question 22

Starch is a polymer of glucose.

Answer 22

It must be broken down into glucose molecules – it is too large to pass through the gut.

Question 23

what are proteins made from

Answer 23

Proteins are made up of amino acids.

they are re assembled in the body through protein synthesis

Question 24

Lipid molecules are too large to pass through the gut wall and must be digested first.

Answer 24

n the body’s cells, they are reassembled into the lipids the cell needs, for instance, for the cell membranes.

Question 25

The human digestive system has two functions:

Answer 25

breaks down complex food substances

provides the very large surface area for maximum absorption of food

Question 26

Mouth

Answer 26

Mouth Begins the digestion of carbohydrates

Question 27

Stomach

Answer 27

Stomach Begins the digestion of protein; small molecules such as alcohol absorbed

Question 28

Large intestine

Answer 28

Large intestine Absorption of water; egestion of undigested food

Question 29

How do enzymes work ?

Answer 29

In an organism, the active site of each enzyme is a different shape. It is a perfect match to the shape of the substrate molecule, or molecules. This is essential to the enzyme being able to work. One enzyme is therefore specific to one substrate’s chemical reaction, or type of chemical reaction.

Question 30

Low temperatures and enzymes

Answer 30

At low temperatures, the number of successful collisions between the enzyme and substrate is reduced because their molecular movement decreases. The reaction is slow.

Question 31

Higher temperatures and enzymes

Answer 31

Higher temperatures disrupt the shape of the active site, which will reduce its activity, or prevent it from working. The enzyme will have been denatured.

Question 32

pH and enzymes

Answer 32

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 33

carbohydrates are broken down into …..

Answer 33

carbohydrate = simple sugars

Question 34

lipids are broken down into …..

Answer 34

lipids = fatty acids + glycerol

Question 35

proteins are broken down into …..

Answer 35

protein = amino acids

Question 36

Bile

Answer 36

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.

Contains sodium hydrogencarbonate, which is an alkali.

It neutralises stomach acid and produces the optimum pH for pancreatic enzymes.

Is produced in the liver, but stored and concentrated in the gall bladder.