B4

Question 1

What is a double circulatory system?

Answer 1

Two circuits joined together, the heart recieves deoxygenated blood and pumps it to the lungs to get filled with oxygen and it comes back as oxygenated blood and then the heart pumps it around the body and returns as deoxygenated blood.

Question 2

What are the walls of the heart mostly made of?

Answer 2

Muscle tissue

Question 3

What are the heart valves?

Answer 3

The heart has valves to make sure that blood is flowing in the right direction - to prevent the backflow of blood

Question 4

Explain the order of blood circulation in the heart

Answer 4

1)Blood flows into the two atria from the
vena cava and the pulmonary vein.

2) The atria contract, pushing
the blood into the ventricles.

3) The ventricles contract, forcing the
blood into the pulmonary artery and
the aorta, and out of the heart.

4) The blood then flows to the organs through
arteries, and returns through veins

5) The atria fill again and the whole cycle starts over.

The heart also needs its own supply of oxygenated blood.
Arteries called coronary arteries branch off the aorta and surround
the heart, making sure that it gets all the oxygenated blood it needs.

Question 5

What is the hearts pacemaker?

Answer 5

1)Your resting heart rate is controlled by a group of cells in the right atrium wall that act as a pacemaker

2) These cells produce a small electrical impulse which spreads to the
surrounding muscle cells, causing them to contract.

Question 6

What are the 3 blood vessels and what do they do?

Answer 6

• Arteries - these carry blood away from the heart at high pressure
• Capillaries - these are involved in the exchange of materials at the tissues
• veins - carry blood to the heart at a lower pressure

Question 7

What do arteries have?

Answer 7

-the walls of arteries are strong and elastic
-the walls are thick compared to the hole down the middle ( lumen )
-they contain thick layers of muscle to make them strong and elastic fibres to allow them to stretch and to spring back.

Question 8

What do capillaries have?

Answer 8

-they have a very thin wall - only one cell thick
-they have a very small lumen
-they branch of from arterys
-they carry blood really close to every cell to exchange substances with them
-they have permeable walls so that substances can diffuse in and out

Question 9

What do veins have?

Answer 9

-elastic fibres and smooth muscle
-they have valves to prevent the backflow of blood
-they are made from capillaries joining up to form veins
-large lumen to help blood flow despite the lower pressure

Question 10

What do red blood cells do? And how are they adapted for their function ?

Answer 10

1)The job of red blood cells is to carry oxygen from the lungs to all the cells in the body.

2)Their shape is a biconcave disc (like a doughnut) this gives a large surface area for absorbing oxygen.

3) They don’t have a nucleus - this allows more room to carry oxygen.

4)They contain a red pigment called haemogoblin

5) In the lungs, haemoglobin binds to oxygen to become oxuhaemogobin. In body tissues, the reverse happens oxyhemoglobin splits up into haemoglobin and oxygen, to release oxygen to the cells.

Question 11

What do white blood cells do?

Answer 11

-they have a nucleus to help fight infection
-they produce antibodies to fight microorganisms
-they also produce antitoxins to neutralise any toxins produced by the microoganisms

Question 12

What do platelets do?

Answer 12

-they help blood clot
-they have no nucleus
-they are small fragments of cells

Question 13

What is plasma ?

Answer 13

-it is a liquid that carries a lot of things : red and white blood cells, platelets, nutrients like glucose and amino acids, carbon dioxide, Urea, hormones, proteins, antibodies and anitoxins produced by white blood cells

Question 14

What is coronary heart disease? And what can help stop it?

Answer 14

It is when the coronary arteries get blocked by layers of fatty material build up therefore blood flow becomes restricted. This causes high blood pressure and a lack of oxygen and nutrients to the heart muscle
Stents are used to treat coronary heart disease as they keep arteries open by squashing the fatty material to one side of the artery therefore there is more space in the centre of the artery. Although there is a chance of an infection during surgery and also a risk of a blood clot appearing near the stent.
Also there are statins which are tablets that regulate/reduce the amount of cholesterol in your blood therefore lowering the chance of fat build up in your arterys. It could have side affects like headaches and memory loss.

Question 15

What are mechanical and biological valves?

Answer 15

As you get older your valves could start getting damaged therefore some people have to get theirs replaced by a valve from an animal ( cow or pig ) or a mechanical one ( man made )

Question 16

What are plants made of?

Answer 16

They are made up of organs like stems, roots and leaves.

Question 17

What are plant organs made out of?

Answer 17

Tissue

Question 18

What are all the tissue found in a plant? And what do they do?

Answer 18

Epidermal tissue - this covers the whole plant and has a waxy cuticle which helps to reduce water loss by evaporation. Also the upper epidermis is transparent so that light can pass through into the palisade layer. Also the lower epidermis is full of little holes called stomata which let CO2 diffuse directly into the leaf.

Palisade mesophyll tissue - this is the part of a leaf where most photosynthesis happens and it has lots of chloroplasts and this means that they will allow the plant to capture the most light.

Spongy mesophyll tissue - contains big air spaces to allow gases to diffuse in and out of cells

Xylem and Phloem - they transport thing like water, mineral ions and food around the plant

Meristem tissue - this is found at the growing tips of shoots and roots and is able to differentiate into lots of different types of plant cell, allowing the plant to grow.

Question 19

How are the structures of the Plant tissues related to their functions?

Answer 19

-The epidermal tissues are covered with a waxy cuticle which helps to reduce water loss by evaporation

-The upper epidermis is transparent so that light passes through it to the palisade layer

-the palisade layer has lots of chloroplasts and this means that they’re near the top of the leaf so they can get the most light

-The xylem and phloem form a network of vascular bundles which deliver water and other nutrients to the leaf and take away glucose produced by photosynthesis

-the tissues of leaves are also adapted for efficient gas exchange for e.g. the lower epidermis is full of little holes called stomata , which let CO2 diffuse directly into the leaf. The opening and closing of the stomata are controlled by the guard cells. The air spaces in the spongy mesophyll tissue increases the rate of diffusion of gases

Question 20

What do phloem tubes do? And what are they made of ?

Answer 20

• They transport food made in the leaves to the rest of the plant for immediate use or storage, the transport goes in both directions and the process is called translocation
• They are made of elongated living cells with small pores in the end walls to allow cell sap to flow through

Question 21

What do xylem tubes do? And what are they made of?

Answer 21

• they are made up of dead cells joined together and they are strengthened with a material called lignin

-they carry water and minerals ions from the roots to the stem and leaves

-the movement of water from the roots, through the xylem and out of the leaves called the transpiration stream

Question 22

What is transpiration?

Answer 22

• transpiration is the loss of water from the plant
• it is caused by the evaporation and diffusion of water from a plants surface and most transpiration happens in the leaves
• water enters through the roots and water evapourates from the leaves when there is too much water in the plant

Question 23

What is transpiration affected by?

Answer 23

• Light intensity - the brighter the light the greater the transpiration rate because the stomata begin to close when its darker
• Temp - the warmer the faster transpiration happens because when its warm water particles have more energy to evaporate and diffuse out of the stomata
• Air flow - the better air flow ( wind ) the greater transpiration rate because diffusion happens from an area of higher to lower concentration
• Humidity - the drier the air around the leaf the faster transpiration happens because if the air is humid then there already is lots of water particles therefore the water cant diffuse out of the stomata

Question 24

What do guard cells do?

Answer 24

-Guard cells open and close the stomata

-When the plant has lots of water the guard cells fill with it and go plump and turgid,
This makes the stomata open so that CO2 can diffuse in and water out

-When the plant is short of water, the guard cells lose water and become flaccid,
making the stomata close. This helps stop too much water vapour escaping.

-Thin outer walls and thickened inner walls make the opening and closing work.

-They’re also sensitive to light and close at night to save water without losing out
on photosynthesis.

-You usually find more stomata on the undersides of leaves than on the top. The lower surface is shaded and cooler - so less water is lost through the stomata than if they were on the upper surface.

-Guard cells are therefore adapted for gas exchange and controlling water loss within a leaf.

Question 25

Explain the breathing process

Answer 25

-The air that you breathe in goes through the trachea.

-This splits into two tubes called bronchi (each one is
a bronchus), one going to each lung.

-The bronchi split into progressively smaller tubes
called bronchioles.

-The bronchioles finally end at small bags called alveoli
where the gas exchange takes place

Question 26

What is an artificial pacemaker?

Answer 26

It is a device that produces an electric current to keep your heart beating normaly

Question 27

How are arteries adapted to suit their functions?

Answer 27

They have a thick muscle layer to make them strong and they have elastic fibres to help them stretch and contract.

Question 28

What is Phagocytosis?

Answer 28

It is the process which a white blood cell binds to and then engulfs a pathogen - in order to destroy it

Question 29

What is artificial blood and what are the main benefits of it and what are the downsides of it ?

Answer 29

Artificial blood is basically a salt water solution.

The main benefit is that it replaces the volume of liquid that you’ve lost, so your heart can continue to pump blood around the body.

The downside is that it doesn’t contain any red blood cells, so can’t carry oxygen.

Question 30

What is blood transfusion ?

Answer 30

A blood transfusion contains real blood, which comes with red blood cells. This is far better, but often not as readily available as artificial blood.

Question 31

At night, why do the stomata close ?

Answer 31

At night, there is no light for photosynthesis, so plants dont need to absorb CO2
This means that they can close their stomata and conserve water

Question 32

How do root hair cells absorb mineral ions ?

Answer 32

Acrive transport

Question 33

How do root hair cells absorb water ?

Answer 33

Osmosis

Question 34

How do gills work in fish and how are they adapted for gas exchange ?

Answer 34

Water (containing oxygen) enters the fish through it’s mouth and passes through the gills.
As this happens, oxygen diffuses from the water into the blood in the gills and carbon dioxide diffuses from the blood into the water

Adaptations:
-Each gill is made from lots of thin plates called gill filaments which give a big surface area for exchange of gases
-The gill filaments are also covered with tiny structures called lamellae, which increase the surface area even more
-The lamellae have lots of capillaries to speed up diffusion and they also have a thin surface layer of cells to minimise the distance that the gases have to diffuse
-The concentration of oxygen in the water is always larger than in the blood so as much oxygen as possible diffuses into the blood

Question 35

Why is translocation important for plants ?

Answer 35

Because sugars (glucose) are made in the leaf so translocation is needed to move the glucose to the rest of the plant from the leaves for respirarion or for storage

Question 36

What is the role of cappilaries ?

Answer 36

The role of capillaries is to exchange nutrients and waste products with the tissues.