B3- Transport systems in plants and animals

Question 1

What does the circulatory system consist of?

Answer 1

the heart - which is the muscular pump that keeps the blood moving around the body
the blood - which carries the substances around the body
the arteries - which carry blood away from the
heart
the veins - which return blood to the heart
the capillaries - which are tiny blood vessels that are close to the body’s cells where exchanges can happen

Question 2

The body has a double circulatory system. What does this mean?

Answer 2

This means that there is one circulation solely for the lungs (in order to oxygenate the blood) and one for the rest of the body. On its journey around the body, blood must go through both circulations.

Question 3

What do valves do?

Answer 3

The one-way valve prevents the blood flowing back to the atrium to stop deoxygenated and oxygenated blood mixing.

Question 4

What is the passage of blood through the heart?

Answer 4

Deoxygenated blood arrives at the left-hand side of the heart:
It enters the heart through the vena cava.
Blood flows into the right atrium.
Blood is pumped into the right ventricle.
Blood is pumped out of the heart, along the pulmonary artery, to the lungs.
Oxygenated blood arrives at the right-hand side of the heart:
.It enters the heart through the pulmonary vein.
.Blood flows into the left atrium.
.Blood is pumped into the left ventricle.
Blood is pumped out of the heart, along the aorta, to the rest of the body.

Question 5

When are artificial or donor valves used?

Answer 5

Occasionally, some people’s heart valves become stiff or leaky, which prevents the valves from functioning properly to prevent the backflow of blood. It is possible to replace the faulty valves with either valves from a biological source or by using mechanical valves.

Question 6

What are the advantages of biological valves?

Answer 6

Do not damage red blood cells as they pass through the open valves

Question 7

What are the disadvantages of biological valves?

Answer 7

Prone to becoming hardened over the course of several years
For patients with long life expectancy, there is a higher chance of further operations to replace the valves (any operation carries risks)

Question 8

What are the advantages of mechanical valves?

Answer 8

Very strong and durable - able to last a lifetime

Question 9

What are the disadvantages of mechanical valves?

Answer 9

Damage red blood cells as they pass through the open valves
Require the patient to take anti-blood clotting drugs for the rest of their life
Some people say they can hear the valves opening and closing

Question 10

Why are artificial hearts used?

Answer 10

In cases where a patient has severe heart disease/damage/failure, a heart transplant is necessary. However, there is often a shortage of compatible heart donors available - meaning that many people die while on the waiting list.Artificial (man-made) hearts provide an alternative as they replicate the function of the heart. But only in the short-term.

Question 11

What are the advantages of artificial hearts?

Answer 11

Prevent people dying on the waiting list

Replicates the function of the heart

Question 12

What are the disadvantages of artificial hearts?

Answer 12

current designs have not proved to be very successful in the long term, and are prone to blood clotting within them so they can only be used in the short time whilst a donor is found.

Question 13

What are the adaptions of the arteries?

Answer 13

Blood in the arteries is under high pressure generated by the heart.
thick walls - to resist the high pressure of the
blood
a thick layer of elastic fibres – to allow the artery to stretch when a surge of blood passes through it, and then recoil in between heart beats to maintain blood pressure
a thick layer of muscle within the wall – to allow blood to be diverted to where it is needed in the body

Question 14

What are the adaptions of the veins?

Answer 14

Blood in the veins is under less pressure.

thin walls as they have blood with a lower pressure flowing through them

one-way valves in them to prevent blood flowing back in the opposite direction

Question 15

What is the name of the heart’s own artery and what does it do?

Answer 15

the coronary artery, which supplies the heart with glucose and oxygen

Question 16

What is the lumen?

Answer 16

The central cavity of a hollow structure in an organism or cell.

Question 17

What happens to people with heart disease?

Answer 17

arteries can become narrower due to the build-up of fatty deposits within the wall of the artery.This has the effect of narrowing the lumen of the artery, reducing the amount of oxygenated blood that can be supplied to the heart muscle.

Question 18

What are stents?

Answer 18

metal grids which can be inserted into an artery to maintain blood flow by keeping the artery open

Question 19

How do you insert stents?

Answer 19

To insert a stent, a catheter with a balloon attached to it is inserted into a blood vessel in the leg. The balloon has the metal stent on it. The catheter is directed to the coronary artery. When the narrowed section of artery is found, the balloon is inflated which causes the stent to expand, and it becomes lodged in the artery. keeping the artery open so that the heart received enough oxygenated blood.

Question 20

What are the advantages and disadvantages of stents?

Answer 20

Stents are good alternatives to more risky operations, like by-pass surgery, providing the patient’s heart disease is not too serious. However, fatty deposits may build up on the stent over time - meaning that blood flow to the heart muscle may be reduced again.

Question 21

What do capillaries do?

Answer 21

Capillaries are the smallest type of blood vessel, and are adapted to allow the effective exchange of substances between the blood and the tissues of the body.

Question 22

How do useful substances diffuse into the capillaries?

Answer 22

Capillaries are made of thin cells, meaning that some parts of the blood can easily leave the capillary, bathing the cells in a fluid known as tissue fluid. Useful substances within the tissue fluid - including glucose, oxygen and amino acids - can then diffuse into the cells down a concentration gradient. The concentration gradient is always maintained as the useful substances are constantly being used up by the cell.

Question 23

How do waste substances diffuse out of the capillaries?

Answer 23

Waste substances generated by the cell diffuse out of the cell, and back into the tissue fluid. Most of the tissue fluid is then reabsorbed back into the blood, and with it the waste substances – such as carbon dioxide and urea – which are taken away to be excreted.

Question 24

How is the concentration gradient maintained in the capillaries?

Answer 24

A concentration gradient is always maintained as the cell constantly generates more waste substances, and the blood constantly takes them away.

Question 25

What is the role of the blood?

Answer 25

to transport substances around our body and to defend against infection by potential pathogens.

Question 26

What is contained in the blood?

Answer 26

Blood is a tissue which includes liquid, cells, cell fragments and solutes. It is made of four constituent parts - red blood cells, white blood cells, platelets and plasma.

Question 27

What are red-blood cells?

Answer 27

Red blood cells are tiny, nucleus-free cells which carry oxygen from the lungs to tissues.

Question 28

How are red-blood cells adapted?

Answer 28

there are huge numbers of red blood cells
the cells are tiny so they can pass through narrow capillaries
the cells have a flattened disc shape to increase surface area - allowing rapid diffusion of oxygen
the cells contain haemoglobin - which transports oxygen and carbon dioxide around the body

Question 29

What happens with the haemoglobin in oxygen rich, and oxygen poor places? (make sure you know the equation)

Answer 29

In oxygen-rich environments (ie the lungs), haemoglobin combines with oxygen to form oxyhaemoglobin. In low-oxygen environments (such as body cells), oxyhaemoglobin releases the oxygen to become haemoglobin again

Question 30

What is the difference in colour of deoxygenated and oxygenated blood?

Answer 30

Blood appears bright red when oxygenated and dark red when deoxygenated.

Question 31

What are white blood cells?

Answer 31

Different types of white blood cells exist. Some white blood cells can engulf bacteria and other pathogens. They can change shape easily and produce enzymes which digest the pathogens.
Other types of white blood cell secrete antibodies and antitoxins to help destroy pathogens.

Question 32

What is blood plasma?

Answer 32

Plasma is a straw-coloured liquid which makes up about 55 per cent of blood. It transports dissolved substances around the body.

Question 33

What are the substances that plasma transports?

Answer 33

hormones
antibodies
nutrients - such as water, glucose, amino acids, minerals and vitamins
waste substances - such as carbon dioxide and urea

Question 34

Where are soluble products of digestion transported?

Answer 34

From the small intestine to the organs of the body.

Question 35

Where is carbon dioxide transported?

Answer 35

From the organs of the body to the lungs

Question 36

Where is urea transported?

Answer 36

From the liver to the kidneys

Question 37

What are platelets?

Answer 37

Platelets are small fragments of cells, but they do not possess a nucleus. They are involved in the process of forming clots at sites where there is a wound, eg a cut or graze.

Question 38

What is Transpiration?

Answer 38

Transpiration is the process by which water evaporates from the leaves, which results in more water being drawn up from the roots.

Question 39

What are vascular bundles?

Answer 39

Plants have two transport systems to move food, water and minerals through their roots, stems and leaves. These systems use continuous tubes called xylem and phloem, and together they are known as vascular bundles.

Question 40

What does the Xylem do?

Answer 40

Xylem vessels are involved in the movement of water through a plant - from its roots to its leaves via the stem.

Question 41

What is the process by which water is transported around the plant?

Answer 41

Water is absorbed from the soil through root hair cells.
Water moves by osmosis from root cell to root cell until it reaches the xylem.
It is transported through the xylem vessels up the stem to the leaves.
It evaporates from the leaves (transpiration).

Question 42

What is the anatomy of the xylem?

Answer 42

The xylem tubes are made from dead xylem cells which have the cell walls removed at the end of the cells, forming tubes through which the water and dissolved mineral ions can flow. The rest of the xylem cell has a thick, reinforced cell wall which provides strength.

Question 43

What does the Phloem vessel do?

Answer 43

Phloem vessels are involved in translocation. Dissolved sugars, produced during photosynthesis, and other soluble food molecules are moved from the leaves to growing tissues (eg the tips of the roots and shoots) and storage tissues (eg in the roots).

Question 44

What does translocation mean?

Answer 44

The transport of dissolved material within a plant.

Question 45

What is the anatomy of the Phloem?

Answer 45

In contrast to xylem, phloem consists of columns of living cells. The cell walls of these cells do not completely break down, but instead form small holes at the ends of the cell. The ends of the cell are referred to as sieve plates. The connection of phloem cells effectively forms a tube which allows dissolved sugars to be transported.

Question 46

What is the transpiration stream?

Answer 46

More water is drawn out of the xylem cells inside the leaf to replace what has been lost. Water molecules have a tendency to stick together – so as water leaves the xylem to enter the leaf, more water is pulled up behind it. This produces a continuous flow of water and dissolved minerals moving up the xylem tube from the roots, up the stem, and into the leaves.

Question 47

How does water move through the roots?

Answer 47

As water moves into the root hair cell down the concentration gradient, the solution inside the root hair cell becomes more dilute. This means that there is now a concentration gradient between the root hair cell and adjacent root cells, so water moves from the root hair cell and into the adjacent cells by osmosis.
This pattern continues until the water reaches the xylem vessel within the root - where it enters the xylem to replace the water which has been drawn up the stem.

Question 48

What are the factors that affect the rate of transpiration and the rate of uptake from the soil?

Answer 48

Light, Temperature, Wind, Humidity

Question 49

How does light affect the rate of transpiration?

Answer 49

The stomata open wider to allow more carbon dioxide into the leaf for photosynthesis. More water is therefore able to evaporate. So transpiration increases.

Question 50

How does temperature affect the rate of transpiration?

Answer 50

Evaporation and diffusion are faster at higher temperatures so transpiration is faster.

Question 51

How does wind affect the rate of transpiration?

Answer 51

Water vapour is removed quickly by air movement, speeding up diffusion of more water vapour out of the leaf. so transpiration is faster.

Question 52

How does humidity affect the rate of transpiration?

Answer 52

Diffusion of water vapour out of the leaf slows down if the leaf is already surrounded by moist air. So transpiration is slower.

Question 53

What happens if the rate of water loss is faster than the rate at which it is supplied by the roots?

Answer 53

then plants can slow down the transpiration rate by closing some of their stomata. This is regulated by guard cells, which lie on either side of a stoma.

Question 54

How to guard cells control the stoma?

Answer 54

If the guard cells are turgid, then they curve forming ‘sausage-shaped’ structures with a hole between them. This is the stoma.
However, if the guard cells are flaccid due to water loss, they shrivel up and come closer together, closing the stoma. This is turn reduces the water loss due to transpiration, and can prevent the plant from wilting.