B2.2

Question 1

Why do large multicellular organisms need transport systems?

Answer 1

They have a small surface area to volume ratio and so the rate of diffusion alone would not be fast enough to transport substances around.

Question 2

Give 4 examples of substances transported within organisms.

Answer 2

Oxygen is transported in for respiration
CO2 is transported out from respiration
Dissolved food molecules from digestion
Urea and waste products.

Question 3

Why do mammals need a double circulatory system?

Answer 3

Double circulatory systems have blood at a higher pressure, allowing it to flow faster and move substances quickly around the body.

Question 4

Describe the double circulatory system in mammals

Answer 4

The heart pumps blood to the lungs, the oxygenated blood returns to the heart and is then pumped around the body.

Question 5

What is the difference in function between veins, arteries and capillaries?

Answer 5

Arteries carry blood away from the heart

Veins carry blood towards the heart

Capillaries flow close to tissues for exchange

Question 6

Describe the structure of arteries

Answer 6

They have thick walls made of muscle and elastic tissue and a small lumen to transport blood under high pressure

Question 7

Describe the structure of capillaries

Answer 7

They have thin walls about one cell thick to allow for the easy exchange of substances at the tissues

Question 8

Describe the structure of veins.

Answer 8

Veins have less muscle and elastic tissue than arteries and they have a larger lumen as the blood is at lower pressure, they also have valves to prevent backflow.

Question 9

Describe the structure of the lungs

Answer 9

The trachea branches into two bronchi
The bronchi branch into bronchioles
These bronchioles end in alveoli which are lined with capillaries for exchange

Question 10

Describe the blood flow through the right side of the heart.

Answer 10

Deoxygenated blood flows into the right atrium from the vena cava
This blood passes through the right AV valve into the right ventricle
The blood is then pumped out of the heart to the lungs through the right SL valve and into the pulmonary artery.

Question 11

Describe the blood flow through the left side of the heart.

Answer 11

Blood enters into the left atrium from the pulmonary vein
The blood is then pumped through the left AV valve into the left ventricle
The blood is then pumped out through the left SL valve and into the aorta

Question 12

What is the name of the wall that separates the right and left sides of the heart?

Answer 12

The septum

Question 13

What is the name of the artery that supplies the heart tissue with blood?

Answer 13

The coronary artery

Question 14

What type of muscle is the heart made of?

Answer 14

Cardiac muscle

Question 15

Why is the wall of the left ventricle thicker than the wall of the right ventricle?

Answer 15

The left ventricle has to pump blood a further distance around the whole body so the blood needs to be under a higher pressure

Question 16

How is plasma adapted as a transport medium?

Answer 16

Plasma is the liquid part of the blood and most molecules transported in blood need to be dissolved in water.

Question 17

Give 3 adaptations of red blood cells to their function

Answer 17

They have a biconcave shape which gives them a large surface area

They have no nucleus so there is more space for haemoglobin

They are very flexible so they can fit through capillaries.

Question 18

How are root hair cells adapted to their function?

Answer 18

Long root hair extension to increase surface area for uptake
Thin membranes to decrease the diffusion distance

Question 19

What does the xylem transport?

Answer 19

Water and minerals

Question 20

State 3 benefits of transpiration

Answer 20

The stream of water cools the plant
The water helps to support the plant by creating turgor pressure
The plant has a constant water supply for photosynthesis

Question 21

How is the xylem adapted to transport water?

Answer 21

It is waterproofed using a substance called lignin.
The xylem cells are dead and have no organelles so there is more space for water.

Question 22

Describe the structure of leaf tissue

Answer 22

At the top and bottom is a waxy cuticle, then working from top to bottom is the:
Upper epidermis
Palisade mesophyll
spongy mesophyll
lower epidermis, and in the middle of the lower epidermis is the guard cells.

Question 23

Describe the process of transpiration

Answer 23

Water is lost through the stomata
More water is drawn up to replace the lost water

Question 24

What is the transpiration stream?

Answer 24

The transpiration stream is the flow of water through a plant.

Question 25

How does temperature affect the rate of transpiration?

Answer 25

As the temperature increases, so does the transpiration rate, the molecules have more KE and evaporation happens faster.

Question 26

How does light intensity affect the rate of transpiration?

Answer 26

The brighter the light, the more stomata are open and the rate of photosynthesis increases which both decrease the amount of water in the plant.
The rate of transpiration increases.

Question 27

How does wind speed affect the rate of transpiration?

Answer 27

The faster the wind speed, the faster the water is moved away from the plant, creating a steeper gradient and increasing the transpiration rate.

Question 28

Describe how to use a potometer to measure transpiration

Answer 28

The plant is placed in the end of an airtight tube containing water.
A single air bubble is introduced to the tube and the movement of the bubble is measured over time.

Question 29

What does the phloem transport?

Answer 29

Sugars like sucrose