TOPIC 2 - ORGANISATION

Question 1

What is muscular tissue?

Answer 1

It contracts to move what it is attached to.

Question 2

What is glandular tissue?

Answer 2

It makes and secretes chemicals like enzymes and hormones.

Question 3

What is epithelial tissue?

Answer 3

Covers some parts of the body eg inside of the gut.

Question 4

What is tissue?

Answer 4

A group of similar cells that work together to carry out a particular function. It can include more than one type of cell.

Question 5

What is an organ?

Answer 5

A group of different tissues that work together to form a certain function.

Question 6

What is an organ system?

Answer 6

An organ system is a group of organs working together to perform a particular function.
For example, the digestive system breaks down and absorbs food. It is made up of these organs:
Glands - produce digestive juices
Stomach and small intestine which digest food
The liver which produces bile
The small intestine which absorbs soluble food molecules.
The large intestine which absorbs water from indigested food leaving faeces.

Question 7

Explain the digestive system as an organ system.

Answer 7

The digestive system breaks down and absorbs food. It is made up of these organs:
Glands - produce digestive juices
Stomach and small intestine which digest food
The liver which produces bile
The small intestine which absorbs soluble food molecules.
The large intestine which absorbs water from indigested food leaving faeces.

Question 8

What are enzymes?

Answer 8

A catalyst is a substance which increases the speed of a reaction, without being changed or used up in a reaction.
They act as biological catalysts.
They are large proteins made up of chains of amino acids. These chains fold into unique shapes, which enzymes need to do their jobs.

Question 9

How do enzymes work?

Answer 9

Usually involves things being split apart or joined together.
Every enzyme has an active site with a unique shape that fits onto the substance involves in a reaction.
Catalysts usually only catalyse one specific reaction.
This is because for the enzyme work, the substrate has to fit in the active site. If the substrate doesn’t match the active site, then the reaction won’t be catalysed.
This is known as the LOCK AND KEY

Question 10

How do temperature and pH effect enzymes?

Answer 10

A higher temperature will increase the reaction rate at first. However, if it gets too hot, the enzyme becomes denatured. This means the active site changes shape, so the substrate won’t fit anymore.
All enzymes have an optimum temperature they work best at.
Enzymes can also become denatured if the pH is too high or too low. All enzymes have an optimum pH that they work best at, this if often 7. However, pepsin is an enzyme in the stomach used to break down proteins. It works best at pH 2, which means it is well suited to the acidic conditions there.

Question 11

What is the practical to investigate the effect of pH on enzyme activity?

Answer 11

The enzyme amylase catalysts the breakdown of starch to maltose. It is easy to detect starch using iodine solution - if starch is present, the iodine solution will change from browny-orange to blue-black. This is how you investigate how pH affects Amylase activity:
-put a drop of iodine solution into every well of the spotting tiles
- place a Bunsen burner on a heat-proof mat, and a tripod and gauze over the Bunsen burner. Put a beaker of water on top of the tripod and heat the water until it is at 35 degrees Celsius. Try to keep the temperature constant throughout the experiment.
Use a syringe to add 1ml of amylase solution and 1ml of a buffer solution with a pH of 5 to a boiling tube. Using a test tube holder, put the tube into the beaker of water and wait for 5 minutes.
Next, use a different syringe to add 5ml of a starch solution to the boiling tube. Immediately mix the contents of the boiling tube and start a stop clock.
-use continuous sampling to record how long it takes for the amylase to break down all of the starch. To do this, use a dropping pipette to take a fresh sample from the boiling tube every 30 seconds and put a drop into a well. When the iodine solution remain browny-orange, starch is no longer present.
Repeat the whole experiment with buffer solution of different pH values to see how pH affects the time taken for the starch to be broken down.
Remember to control any variables each time (eg concentration and volume of amylase solution) to make it a fair test.

Question 12

What is the formula to calculate the rate of a reaction?

Answer 12

Rate = 1000/time.

Question 13

What does the enzyme carbohydrase do?

Answer 13

Carbohydrases convert carbohydrates into simple sugars.
Eg amylase is an example of carbohydrase. It breaks down starch.
Amylase is made in the salivary glands, pancreas, and the small-intestine

Question 14

What does the enzyme protease do?

Answer 14

Proteases convert proteins into amino acids.

Proteases are made in three places: the stomach (pepsin), the pancreas and the small intestine.

Question 15

What do the enzyme lipase do?

Answer 15

Lipases convert lipids into glycerol and fatty acids.

Lipases are made in two places: the pancreas and the small intestine.

Question 16

What does bile do?

Answer 16

Bile neutralises the stomach acid and emulsifies fats.
Bile is produced in the liver. It is stored in the gall bladder before it is released into the small intestine.
The hydrochloric acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly. Bile is alkaline - it neutralises the acid and makes conditions alkaline. The enzymes in the small intestine work best in these alkaline conditions. It emulsifies fats. This means it breaks the fat into tiny droplets. This gives a much bigger surface area of fat for the enzyme lipase to work on - which makes digestion faster.

Question 17

What enzymes are in the salivary glands?

Answer 17

The salivary glands produce amylase enzyme in the saliva.

Question 18

What does the liver do?

Answer 18

The liver is where bile is produced. Bile neutralises acids and emulsifies fats.

Question 19

What does the stomach do?

Answer 19

It pummels the food with its muscular walls.
It produces protease enzyme, pepsin.
It produces hydrochloric acid for two reasons:
- to kill bacteria
- to give the right pH for the protease enzyme to work (pH 2 — acidic).

Question 20

What does the pancreas do?

Answer 20

The pancreas produces protease, amylase and lipase enzymes. It releases these into the small intestine.

Question 21

What does the gall bladder do?

Answer 21

The gall bladder is where bile is stored, before it is released into the small intestine.

Question 22

What does the small intestine do?

Answer 22

The small intestine produces protease, amylase and lipase enzymes to complete digestion.
This is also where the digested food is absorbed out of the digestive system into the blood.

Question 23

What does the large intestine do?

Answer 23

The large intestine is where excess water is absorbed from the food.

Question 24

What does the rectum do?

Answer 24

The rectum is where the faeces are stored before until they leave through the anus.

Question 25

How can you prepare a food sample for food testing?

Answer 25

Get a piece of food and break it up using a pestle and mortar. Transfer the ground up food to a beaker and add some distilled water. Give the mixture a good stir with a glass rod to dissolve some of the food. Filter the solution using a funnel lined with filter paper to get rid of solid bits of food.

Question 26

What test do you do to test for sugars?

Answer 26

You use the Benedictus test for sugars. (For reducing sugars) Prepare a food sample and transfer 5cm*3 to a test tube. Prepare a water bath so it is set for 75 degrees Celsius. Add some Benedictus solution (about 10 drops) to the solution using a pipette. Place the test tube in the water bath using a test tube holder and leave it in there for 5 mins. Make sure the tube is pointing away from you. If the food sample contains a reducing sugar, the solution in the test tube will change from the normal blue colour to green, yellow or brick-red. The colour change spends on how much sugar is in the food.

Question 27

What test do you do for starch?

Answer 27

Use iodine solution to test for starch. Make a food sample and transfer 5cm*3 of your sample to a test tube. Then add a few drops of iodine solution and gently shake the tube to mix the contents. If the sample contains starch, the colour of the solution will change from browny-orange to black or blue-black.

Question 28

What test can you do to test for proteins?

Answer 28

Use the biuret test to test for proteins. Prepare a sample of your food and transfer 2cm*3 of your sample to a test tube. Add 2cm*3 of biuret solution to the sample and mix the contents of the tube by gently shaking it. If the food sample contains protein, the solution will change from blue to pink or purple. If no protein is present, the solution will stay blue.

Question 29

What food test do you do for lipids?

Answer 29

Use the Sudan III test for lipids. Prepare a food sample (you don’t need to filter it). Transfer 5cm*3 into a test tube. Use a pipette to add 3 drops of Sudan III stain solution to the test tube and gently shake the tube. Sudan III stain solution stains lipids. If the sample contains lipids, the mixture will separate out into two layers. The top layer will be bright red. If no lipids are present, no separate red layer will form at the top of the liquid.

Question 30

Explain the lungs and their role.

Answer 30

The lungs are protected by the rib cage and are surrounded by pleural membranes. The air enters 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 31

How do the alveoli carry out gas exchange in the body?

Answer 31

The lungs contain millions of alveoli, surrounded by a network of capillaries. This is where gas exchange happens. The blood passing next to the alveoli has just returned from the rest of the body, so it contains lots of carbon dioxide. Oxygen diffuses out of the alveolus into the blood across the concentration gradient. Carbon dioxide diffuses out of the blood into the alveolus to be breathes out. When the blood reaches body cells oxygen is released from the red blood cells and diffuses into the body cells. At the same time, carbon dioxide diffuses out of the body cells into the blood. It is then carries back to the lungs.

Question 32

How do you calculate number of breathes per minute?

Answer 32

Breather per minute = number of breathes / number of minutes.

Question 33

Explain the heart as a double circulatory system?

Answer 33

The right ventricle pumps deoxygenated blood to the lungs to take in oxygen. The blood them returns to the heart. On the other side, the left ventricle pumps oxygenated blood to the rest of the body and other organs. The blood gives up its oxygen at the body cells and deoxygenated blood returns to the heart to be pumped to the lungs again.

Question 34

Explain the blood flow through the heart.

Answer 34

Blood flows into the atria fro the vena cava and pulmonary vein. The atria contract, pushing the blood into the ventricles. The ventricles contract, forcing the blood into the pulmonary after and the aorta and out of the heart. The blood then flows to the organs through arteries, and returns through veins. The atria fill again and start over.

Question 35

What artery ensures the blood has its own supply of oxygenated blood?

Answer 35

Coronary arteries.

Question 36

What is the pacemaker in the heart?

Answer 36

Your resting heart rate is controlled by a group of cells in the right atrium wall that act as a pacemaker. These cells produce a small electric impulse which spreads to the surrounding muscle cells, causing them to contract. An artificial pacemaker if often used to control heartbeat of the natural pacemaker cells don’t work properly (eg if the patient has an irregular heartbeat). It is a little device that’s implanted under the skin and has a wire going to the heart. It produces an electric current to keep the heart beating regularly.

Question 37

What are the three blood vessels?

Answer 37

Arteries - carry look away from the heart Capillaries - these are involved in the exchange of materials at the tissues Veins - these carry blood to the heart.

Question 38

Explain arteries.

Answer 38

Arteries carry blood under pressure. This is because the heart pumps the blood out at high pressure so the artery walls are strong and elastic. The walls are thick compared to the size of the lumen. They contain thick layers of muscle to make them strong and elastic fibres to allow them to stretch and spring back.

Question 39

Explain capillaries.

Answer 39

Arteries brace into capillaries. They are very small. They carry blood really close to every cell in the body to exchange substances with them. They have permeable walls, so substances can diffuse in and out. They supply food and oxygen, and take away wats like carbon dioxide. Their walls are usually only one cell thick. This increases the rate of diffusion by decreasing distance over which it occurs.

Question 40

Explain veins.

Answer 40

Capillaries eventually join up to form veins. The blood is at low pressure in the veins so the walls don’t need to be as thick as artery walls. They have a bigger lumen than arteries to help the blood flow despite the low pressure. They also have valves to prevent the back flow of blood/keep it flowing in the right direction.

Question 41

How do you calculate rate of blood flow?

Answer 41

Rate of blood flow = volume of blood / number of minutes.

Question 42

Describe red blood cells.

Answer 42

Their job is to carry oxygen from the lungs to all the cells in the body. Their shape is called the biconcave disc which gives a large surface area for absorbing oxygen. They don’t have a nucleus which allows them to have more room to store oxygen. They contain a red pigment called haemoglobin. In the lungs, haemoglobin binds to the oxygen to become oxyhaemoglobin. In body tissues, the reverse happens - oxyhaemoglobin splits up into haemoglobin and oxygen, to relaxed oxygen to the cells.

Question 43

What is the purpose of white blood cells?

Answer 43

White blood cells defend against infection. Some change shape to consume/engulf the unwanted microorganisms PHAGOCYTOSIS Some produce antibodies to fight microorganisms, as well as antitoxins to neutralise any toxins. They have a nucleus.

Question 44

What do platelets do?

Answer 44

Platelets help blood clot. They are small fragments of cells. They have no nucleus. They help the blood clot at a wound - to stop the rapid loss of blood and to prevent microorganisms getting in. A lack of platelets can cause excessive bleeding or bruising.

Question 45

What is plasma?

Answer 45

Plasma is a liquid they carries everything in the blood. It carries: Red and white blood cells and platelets. Nutrients like glucose and amino acids - these are the soluble products of digestion which are absorbed from the gut and taken to cells of the body. Carbon dioxide from the organs to the lungs. Urea from the liver to the kidneys Hormones Proteins Antibodies and antitoxins produces by the white blood cells.

Question 46

How do stents help with cardiovascular disease?

Answer 46

Stents keep the arteries open. They are inserted inside the arteries. They keep them open, making sure blood can pass through to the heart muscles. This keeps the person’s heart beating. They are a way of losing the risk of having a heart attack in people with coronary heart disease. They are effective for a long time and recovery time from surgery is relatively quick. However, there is a risk of complications during the operation and a risk of infection from surgery. There is also a risk of developing a blood clot near the stent. This is called THROMBOSIS.

Question 47

What is coronary heart disease?

Answer 47

Coronary heart disease is when the coronary artery that supplies blood to the muscle of the heart gets blocked by a layer of fatty material building up. This causes the arteries to become narrow, so blood flow is restricted and there is a lack of oxygen to the heart muscle. This can result in a heart attack.

Question 48

What do statins do?

Answer 48

Cholesterol is an essential lipid that your body produces and needs to function properly. However, too much of a certain type of cholesterol (known as LDL cholesterol) can cause health problems. Having too much can cause fatty deposits to form inside the arteries, which can lead to coronary heart disease. Statins are drugs that can reduce the amount of ‘bad’ cholesterol present in the blood stream. This slows down the rate of fatty deposits forming.

Question 49

What are the advantages of statins?

Answer 49

Reduces the risk of strokes, coronary heart disease and heart attacks. As well as reducing the amount of ‘bad’ cholesterol, stains can increase the amount of a beneficial type of cholesterol (known as HDL cholesterol). This type can remove the ‘bad’ cholesterol from the blood. They may also help to prevent other diseases.

Question 50

What are some disadvantages of statins?

Answer 50

They are a long term drug that needs to be taken regularly. There is a risk that someone could forget to take them. They may have negative side effects such as headaches. Some might be serious such as kidney failure. The effect of statins isn’t instant. It takes time for their effect to kick in.

Question 51

Explain the role of an artificial heart.

Answer 51

Doctors may perform a heart transplant using donor organs from people who have recently died. However, if donor organs aren’t available straight away, or they are not the best option, doctors might fit an artificial heart. They are mechanical devices that pump for a person whose own heart has failed. They’re usually only a temporary fix, to keep a person alive until a donor heart can be found or a person can recover by allowing their heart to rest.

Question 52

What are some advantages of an artificial heart?

Answer 52

They are less likely to be rejected by the body’s immune system than a donor heart. This is because they are made from metals or plastics, so the body doesn’t recognise them as foreign and attack in the same way it does living tissue.

Question 53

What are some disadvantages of artificial hearts?

Answer 53

Surgery can lead to bleeding and infection. They don’t work as well as a he,stay natural one - parts of the heart could wear out or the electrical motor could fail. Blood does not flow through artificial hearts as smoothly, which can cause blood clots and lead to strokes. The patient has to drugs to thin their blood and make sure this doesn’t happen, which can cause problems with bleeding if they’re hurt in an accident.

Question 54

Explain how faulty valves can be replaced with biological or mechanical valves.

Answer 54

The valves in the heart can be damaged or weakened by heart attacks, infection or old age. The damage may cause the valve tissue to stiff in, so it won’t open properly. Or a valve may become leaky, allowing blood to flow in both direction, rather than just forward. This means that blood won’t circulate as effectively as normal. Severe valve damage can be treated by replacing the valve. They can be taken from humans or other mammals (eg cows or pigs) - these are biological valves. Or they can be man-made which are mechanical valves. There can still be problems with blood clots as it is a major surgery.

Question 55

What are communicable diseases?

Answer 55

Communicable diseases are those that can spread from person to person or between animals and people. They can be caused by things such as bacteria, viruses, parasites and fungi. They’re are sometimes described as contagious or infectious diseases. Eg measles and malaria.

Question 56

What are non-communicable diseases?

Answer 56

Non-communicable diseases cannot spread between people or animals. They generally last for a long time and get worse slowly. Asthma, cancer and coronary heart disease are example of non-communicable diseases.

Question 57

What factors can affect your health?

Answer 57

Diet Stress Life situation eg access to medicines or condoms to prevent STDs.

Question 58

What is cancer?

Answer 58

Uncontrolled cell growth and division.

Question 59

What does benign mean?

Answer 59

Where the tumour continues to grow until there is no more room. The tumour stays in one place (usually within a membrane) rather than invading other tissues in the body. This type is g normally dangerous, and the tumour isn’t cancerous.

Question 60

What does malignant mean?

Answer 60

Where the tumour grows and spread to neighbouring healthy tissues. Cells can break off and spread to other parts of the body by travelling in the bloodstream. The malignant cells then invade healthy tissues elsewhere in the body forming secondary tumours. Malignant tumours are dangerous and can be fatal - they are cancerous.

Question 61

What is the epidermal tissue in a plant?

Answer 61

This covers the whole plant.

Question 62

What is the palisade mesophyll tissue in the plant?

Answer 62

The part of the leaf where most of photosynthesis happens.

Question 63

What is the spongy mesophyll tissue in the plant?

Answer 63

In the leaf, it contains big air spaces to allow gases to diffuse in and out of cells.

Question 64

What are the xylem and phloem in the plant?

Answer 64

They transport water, mineral ions and food around the plant (through the roots, stems and leaves).

Question 65

What is the meristem tissue in the plant?

Answer 65

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 66

How is the upper epidermis structured?

Answer 66

Covered with a waxy cuticle high helps reduce water loss by evaporation.

Question 67

How is the palisade layer structures?

Answer 67

Has lots of chloroplasts. They’re are. Eat the top of the light to have access to light for photosynthesis.

Question 68

How are the xylem and phloem structured?

Answer 68

They form a network of vascular bundles. They deliver water and other nutrients to the entire leaf and take away glucose produced by photosynthesis. They also help to support the structure.

Question 69

Explain phloem tubes in a plant.

Answer 69

Phloem tubes transport food. Made up of columns of elongated living cells with small pores in the end walls to allow cell sap to flow through. They transport food substances (mainly dissolved sugars) made in the leaves to the rest of the plant for immediate use (eg in growing regions) or for storage. The transport goes in both directions. This process is called translocation.

Question 70

Explain the xylem tubes.

Answer 70

Xylem tubes take up water. Made of dead cells joined end to end with no end walls between them and a hole down the middle. They’re strengthened with a material called lignin. They carry water and mineral ions from the roots to the stem and leaves. The movement of water from the roots, through the xylem and out of the leaves is called the transpiration stream.

Question 71

What is transpiration?

Answer 71

Transpiration is the loss of water from the plant. It is caused by the evaporation and diffusion of water from the p,ants surface. Most transpiration happens in the leaves. This evaporation creates a slight shortage of water in the leaf, and so more water is drawn up from the rest of the plant through the xylem vessels to replace it. In turn, this means more water is drawn up from the roots, and so there is a constant transpiration stream of water.

Question 72

What four factors affect transpiration?

Answer 72

Light intensity Temperature Air flow Humidity

Question 73

How does light intensity affect the rate of transpiration?

Answer 73

The brighter the light, the greater the transpiration rate. Stomata begin to close as it gets darker. Photosynthesis can’t happen in the dark, so they don’t need to be open to let carbon dioxide in. When the stomata are closed,very little water can escape.

Question 74

How does temperature affect the rate of transpiration?

Answer 74

The warmer it is, the faster the rate of photosynthesis. When it is warm the particles have more energy to evaporate and diffuse out of the stomata.

Question 75

How does air flow affect the rate of transpiration?

Answer 75

The better the air flow around the leaf, the greater the transpiration rate. If air flow around the leaf is poor, the water vapour just surrounds the leaf as well as inside it, do diffusion doesn’t happen quickly. If there is good air flow, the water vapour is swept away, maintaining a low concentration of water in the air outside the leaf. Diffusion happens quickly as there is a concentration gradient.

Question 76

How does humidity affect transpiration rate?

Answer 76

The drier the air outside the leaf, the faster transpiration happens. If the air is humid there is already lots of water in the air, so there isn’t a string concentration gradient. So, if the air is drier there is a steeper concentration gradient so diffusion will happen quicker.

Question 77

How are guard cells adapted to open and close the stomata?

Answer 77

They have a kidney shape which opens and closes the stomata in the leaf. When the plant has lots of water the guard cells fill with it and go turgid. This makes the stomata open so gases can be exchanged for photosynthesis. When the plant is short of water, the guard cells lose water and become flaccid, a king the stomata close. This helps to stop too much water escaping. Thin outer walls and thickened inner walls make the opening and closing work. They are also sensitive to light and close at night to save water without losing out on photosynthesis. Usually more stomata on the undersides of the leaves - the underside is cooler so less water is lost through the stomata than if they were on the upper surface. Therefore, guard cells are adapted for gas exchange and controlling water loss within a leaf.