Transport in humans

Question 1

What is the definition of diffusion

Answer 1

Diffusion is the net movement of molecules from a region of higher concentration to a region of lower
concentration.

Question 2

Name four factors that affect the speed of diffusion

Answer 2

Temperature, concentration gradient, surface area, volume

Question 3

How does temperature affect diffusion

Answer 3

At higher temperatures, molecules have more kinetic energy and so move faster. Therefore diffusion occurs faster

Question 4

How does concentration gradient affect diffusion

Answer 4

If there is a very large difference in concentration between two areas, molecules will diffuse from the higher to the lower concentration quickly

Question 5

how does surface area affect diffusion

Answer 5

A large surface area speeds up the rate of diffusion, as there is more space for the molecules to move

Question 6

how does volume affect diffusion

Answer 6

diffusion takes longer if it has to fill a large volume, as molecules have further to move

Question 7

What happens as cells and organisms get bigger to the volume and surface area

Answer 7

Both surface area and volume increase, volume increases much faster, less diffusion

Question 8

What is the circulatory system used for

Answer 8

To transport substances around the body; oxygen and nutrients are transported from exchange surfaces to all the cells and waste products
from cells to the lungs and kidneys.

Question 9

What three things does the circulatory system need to carry out its job

Answer 9

• A liquid to transport substances in – the blood
• A pump to move the liquid – the heart
• A series of pipes to direct the liquid and move it efficiently – the blood vessels

Question 10

What type of circulation do humans have?

Answer 10

Humans have a double circulation. The heart pumps blood twice, sending it through two different circulatory circuits.

Question 11

What is pulmonary circulation

Answer 11

Blood returning from the body (deoxygenated) is pumped to the lungs, where oxygen is gained and carbon dioxide is lost, and then returned to the heart

Question 12

In what order do the arteries/veins go in

Answer 12

Heart to the aorta, then hepatic artery to the hepatic vein and hepatic portal vein, then the renal artery to the renal vein, all body veins lead to vena cava, which goes to pulmonary artery in lungs, then through pulmonary vein to heart and cycle repeats

Question 13

What animals have a single circulatory system?

Answer 13

Animals with high metabolic rates like mammals and birbos

Question 14

What is blood composed of?

Answer 14

plasma, white blood cells, platelets, red blood cells

Question 15

What is plasma?

Answer 15

Plasma is a straw coloured liquid; mainly water, it contains a wide range of dissolved and suspended molecules. As well as transporting the blood cells,
plasma carries: dissolved nutrients such as glucose and amino acids; dissolved waste products including urea and carbon dioxide;

Question 16

What are RBCs

Answer 16

Red blood cells (erythrocytes) are highly specialised cells, which are made in the bone marrow and only live for around 100 days before being destroyed by the liver or
spleen. Their function is to transport oxygen.

Question 17

What are the qualities of RBCs

Answer 17

Red blood cells contain haemoglobin. This is an iron-containing protein which combines with oxygen to form oxyhaemoglobin. Red blood cells are biconcave (discs with a dip in the
middle); this increases their surface area: volume ratio and decreases the distance to the centre of the cell. They have no nucleus, meaning that more haemoglobin can be packed into each cell and so
more oxygen can be transported.

Question 18

What are platelets

Answer 18

Platelets are small cell fragments which help to form clots, preventing blood loss and infection.

Question 19

What are WBCs

Answer 19

White blood cells destroy pathogens which infect our bodies – they are an essential part of the immune system.

Question 20

What’s the function of the heart

Answer 20

The function of the heart is to pump blood around the body, through the blood vessels.

Question 21

Where in the lungs does diffusion occur?

Answer 21

The alveolus, The oxygen diffuses into the blood because the blood is mainly deoxygenated, and therefore has a lower concentration of oxygen.

Question 22

What is osmosis

Answer 22

Water-diffusion, movement of free water particles from an area of high concentration to an area of low concentration over a semi-permeable membrane

Question 23

What happens to free water particles

Answer 23

They attach to the sugar, less free water molecules

Question 24

What is a cell water potential

Answer 24

‘Water potential’ is a measure of the concentration of free water molecules in a solution. Pure water has a water potential of zero. As a solute is added, water potential falls as there will be a
lower concentration of free water molecules.

Question 25

What is an isotonic solution

Answer 25

the solution outside the cell has the same water potential as inside the cell - no
net movement

Question 26

What is a hypotonic solution

Answer 26

the solution outside the cell has a higher water potential then inside the cell - net movement of free water particles into the cell

Question 27

What is a hypertonic solution

Answer 27

the solution outside the cell has a lower water potential then inside the cell - net movement of free water particles out of the cell

Question 28

What is a turgid cell

Answer 28

Non-woody plants rely on their cells being turgid in order to support themselves. If a plant loses a lot of water and cannot replace it via its roots, the cells of the plant will slowly become plasmolysed.

Question 29

What is a plasmolysed cell

Answer 29

As this happens, the turgor pressure inside the cells falls and so cannot support the plant’s weight. Therefore the plant wilts.

Question 30

What is active transport

Answer 30

Active Transport is the movement of

molecules from an area of low concentration to an area of high concentration using energy (via a carrier protein)