B2- Organisation

Question 1

Large multicellular organisms are made up of what?

Answer 1

Organ systems

Question 2

What is the hierarchy of living organisms?

Answer 2

Specialised cells form tissues, which form organs, which form organ systems. Large multicellular organisms have different systems inside of them exchanging and transporting materials.

Question 3

What is a tissue?

Answer 3

A tissue is a group of similar cells that work together to carry out a particular function. Examples include: muscle tissue, glandular tissue and epithelial tissue.

Question 4

What is an organ?

Answer 4

An organ is a group of different tissues that work together to perform a certain function. For example a stomach is made out of: muscular tissue, glandular tissue and epithelial tissue

Question 5

What is an organ system?

Answer 5

An organ system is a group of organs working together to perform a particular function. For example the digestive system is made up of organs such as: glands, stomach, small and large intestine. Organ systems work together to make complete organisms.

Question 6

What is an organism?

Answer 6

An organism is the highest level of organisation in a multicellular organism , consisting of several organ systems

Question 7

What is a catalyst?

Answer 7

A catalyst is a substance which increases the speed of a reaction, without being changed or used up in a reaction.

Question 8

What is an enzyme?

Answer 8

Enzymes are considered biological catalysts as they speed up the rate of reactions.

Question 9

Explain how enzymes work

Answer 9

Chemical reactions usually involve things being split apart or joined together. Every enzyme has an active site with a unique shape that fits onto the substance involved in a reaction. Enzymes can only catalyse one specific reaction. This is because for the enzyme to work the substrate has to fit into its unique active site. If the substrate doesn’t match the enzyme’s active sight then the reaction won’t be catalysed. The substrate enters the active site of an enzyme. The enzyme catalysed the reaction remaining unchanged after reaction producing products.

Question 10

Explain how enzymes need the right temperature and pH

Answer 10

Increasing the temperature of a working enzyme initially increases the activity. Enzymes have an optimum temperature and once this is reached, the activity decreases. Then past a certain temperature, the active site changes shape, and the enzyme is denatured.

The pH also affects enzymes. If it’s too high or too low, the pH interferes with the bonds holding the enzyme together. This changes the shape of the active sight and denatured the enzyme.

Question 11

What are the factors that affect the rate of enzyme action?

Answer 11

Temperature and pH

Question 12

What are digestive enzymes?

Answer 12

Digestive enzymes catalyse the breakdown of large, insoluble food molecules into smaller, soluble molecules.

Question 13

What do carbohydrases do? And explain the example of amylase

Answer 13

Carbohydrases covert carbohydrates into simple sugars. Amylase is an example of carbohydrase. It breaks down starch. Amylase is made in three places: the salivary glands, the pancreas and the small intestine.

Question 14

What do proteaseses do?

Answer 14

Proteases covert proteins into amino acids. Proteins are made in three main places: the stomach, the pancreas and the small intestine.

Question 15

What do lipases 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 is bile and emulsification?

Answer 16

Bile is produced in the liver. It’s stored in the gall bladder before it’s 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 would work best in these alkaline conditions.

It’s emulsifies fats. It breaks the fat into tiny droplets this gives a much bigger surface area of fat for the enzymes lipase to work on which makes its digestion faster.

Question 17

Why is it necessary to break down large insoluble food molecules into smaller soluble molecules?

Answer 17

Large insoluble food molecules can’t be absorbed into the bloodstream. Small soluble molecules can be absorbed into the bloodstream and are used to construct new carbohydrates, proteins and lipids in the body. Some glucose produced by digestion is used for respiration

Question 18

How can you test for sugar?

Answer 18

To test for sugar, add Benedict’s reagent and heat for about two minutes. It will turn any of green, yellow or red sugar is present. The colour depends on the concentration.

Question 19

How do you test for starch?

Answer 19

To test for starch, add iodine solution. It will turn blue – black if starch is present

Question 20

How do you test for proteins?

Answer 20

To test for proteins, add Biuret solution. It will turn mauve or purple if proteins are present

Question 21

How do you test for lipids?

Answer 21

To test for lipids, add Sudan lll (a fat soluble dye) if lipids are present, a red- stained oil layer will float on the water surface. The presence of lipids can also be tested by adding ethanol. The solution is added to water and shaken. If the solution turns cloudy, lipids are present.

Question 22

How are enzymes used in the digestive system?

Answer 22

Enzymes used in the digestive system are produced by specialised cells in glands and in the gut lining. Different enzymes catalyse the breakdown of different food molecules.

Question 23

How are salivary glands used in the digestive system?

Answer 23

Salivary glands produce amylase enzyme in the saliva.

Question 24

How is the stomach used in the digestive system?

Answer 24

It pummels the food with it’s muscular walls. It produces the protease enzyme, pepsin. It produces hydrochloric acid for two reasons: to kill bacteria and to give the right pH for the protease enzyme to work

Question 25

How is the liver used in the digestive system?

Answer 25

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

Question 26

How is the gall bladder used in the digestive system?

Answer 26

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

Question 27

How is the large intestine used in the digestive system?

Answer 27

It is where excess water from the foods are absorbed.

Question 28

How is the rectum used in the digestive system?

Answer 28

It is where the faeces are stored before departing through the anus.

Question 29

How is the small intestine used in the digestive system?

Answer 29

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

Question 30

How is the pancreas used in the digestive system?

Answer 30

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

Question 31

List all the components of the digestive system?

Answer 31

Salivary glands,stomach, gullet, liver, gallbladder, pancreas, large intestine, small intestine, rectum

Question 32

How do the lungs work?

Answer 32

. The thorax is the top part of the body. It’s separated from the lower part of the body by the diaphragm.
. The lungs are protected by the ribcage and surrounded by the pleural membranes
. The air that is breathed in goes through the trachea and splits of into two tubes called bronchi (individually called bronchus) each going to each lung
. The bronchi split off into progressively smaller tubes called bronchioles. These finally end at small bags called alveoli where the gas exchange takes place.

Question 33

How are the alveoli adapted to carry out gas exchange in the body?

Answer 33

.Alveoli are little sacs of air that are contained in the lungs, surrounded by a network of capillaries. This is where gas exchange happens.
. The blood passing next to the alveoli has just returned from the lungs so it contains lots of carbon dioxide and very little oxygen. Oxygen diffuses out of the alveolus (high concentration) to the blood( low concentration). Carbon dioxide diffuses out of the blood (high concentration) into the alveolus (low concentration) to be breathed out.
. When the blood reaches body cells oxygen is released from the red blood cells and diffuses into the body cells (high to low concentration). It’s then carried back to the lungs.

Question 34

What is the circulatory system and what is it made up of?

Answer 34

.The circulatory system carries food and oxygen to every cell in the body. It also carries waste products to where they can be removed from the body

. The circulatory system is made up of the heart, blood vessels and blood. Humans have a double circulatory system as it’s two circuits joined together.

. In the first one, the right ventricle pumps deoxygenated blood to the lungs to take in oxygen. The blood then returns to the heart

. In the second one, the left ventricle pumps oxygenated blood around all the other organs of the body. The blood gives up it’s oxygen to the body cells and the deoxygenated blood returns to the heart to be pumped out of the lungs again

Question 35

Explain how the heart pumps blood around the body

Answer 35

.The heart is a pumping organ that keeps the blood flowing around the body. The walls of the heart are mostly made up of muscle tissue.
.The heart has valves to make sure that blood flows in the right direction-they prevent it flowing backwards

Question 36

How does the heart use its four chambers?

Answer 36

. This is how the heart uses it’s four chambers (right atrium, right ventricle, left ventricle and left atrium) to pump blood around:

• Blood flows into the two atria from the vena cava and the pulmonary vein. The atria contract, pushing the blood into the ventricles. The ventricle contract, forcing the blood into the pulmonary artery and the aorta, and out of the heart. The blood then flows to the organs through arteries , and returns through veins. The atria then fill again and the whole cycle starts again
• 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 get’s all the oxygenated blood it needs.

Question 37

Explain how the heart is a pacemaker and what an artificial pace maker does.

Answer 37

The 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 is often used to control heartbeat if the natural pacemaker cells don’t work properly. It’s 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 38

What are three main different types of blood vessel?

Answer 38

Arteries, capillaries and veins.

Question 39

What do arteries do and how are they adapted?

Answer 39

Arteries carry blood away from the heart. 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 40

What do capillaries do and how are they adapted?

Answer 40

Capillaries are involved in the exchange of materials at the tissues. Arteries branch into capillaries. They are extremely small. They carry the 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 waste like co2. Their walls are usually only one cell thick. This increases the rate of diffusion by decreasing the distance over which it occurs.

Question 41

What do veins do and how are they adapted?

Answer 41

Veins carry blood to the heart. Capillaries eventually join up to form veins. The blood is at a lower pressure in the veins so 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 lower pressure. They also have valves to keep the blood flowing in the right direction.

Question 42

What are blood cells and how do they function?

Answer 42

The job of red blood cells is to carry oxygen from the lungs to all of the cells in the body. Their shape is a biconcave disc which gives them a large surface area for absorbing oxygen. They also have no nucleus which allows them more room to carry oxygen.

They contain a red pigment called haemoglobin. In the lungs haemoglobin binds to the oxygen to become oxyhemoglobin. In body tissues, the reverse happens where oxyhemoglobin splits up into haemoglobin and oxygen to release oxygen from the cells.

Question 43

What are white blood cells and how do they function?

Answer 43

White blood cells defend against infection.

Some of them can change to gobble up unwelcome microorganisms, in a process called phagocytosis.

Others produce antibodies to fight microorganisms as well as antitoxins to neutralise any toxins produced by the microorganisms.

Unlike red blood cells they do have a nucleus.

Question 44

What are platelets?

Answer 44

Platelets help blood clot. They are small fragments of cells. They have no nucleus. They help the blood to clot at a wound to stop blood pouring out and microorganisms to get in. Lack pf platelets can cause excessive bleeding an bruising.

Question 45

What is plasma?

Answer 45

Plasma is the liquid that carries everything in the blood. It is a pale-straw coloured liquid which carries:

• red and white blood cells and platelets
• nutrients like glucose and amino acids
• co2
• urea
• hormones
• proteins
• antibodies and antitoxins

Question 46

What is cardiovascular disease?

Answer 46

Cardiovascular disease is the disease of the heart or blood vessels.

Question 47

Explain how stents help coronary heart disease

Answer 47

Coronary heart disease is when the coronary arteries that supply the blood to the muscle of the heart get blocked by layers of fatty material building up. This causes the arteries to become narrow, so blood flow is restricted and there’s a lack of oxygen to the heart muscle which can result in a heart attack.

Stents are tubes that are inserted inside arteries. They keep them open making sure that blood can pass through to the heart muscles. This keeps the person’s heart beating.
Stents are a way of lowering the risk of a heart attack in people with coronary heart disease. They are effective and the recovery time from the surgery is relatively quick.

On the down side there is a risk of complications during the operation such as an infection from the surgery. There is also the risk of patients developing a blood clot near the stent, which is called thrombosis

Question 48

How do statins reduce cholesterol in the blood?

Answer 48

Cholesterol is an essential lipid that the human body needs to produce and needs to function properly. However, too much of a certain type of cholesterol can cause health problems. Having too much of this bad cholesterol can cause fatty deposits to develop inside arteries, which can lead to coronary disease.

Statins are drugs that can reduce the amount of bad cholesterol present in the bloodstream. They slow down the rate of fatty deposits forming.

Good-By reducing the amount of bad cholesterol in the blood, statins can reduce the risk of strokes,coronary heart disease and heart disease. They also can increase the amount of beneficial cholesterol in your bloodstream. This type can remove bad cholesterol from the blood. They also prevent the risk of some
other diseases.

Bad- statins have to be taken regularly as they’re long term so some people might forget to take them. Statins can have some negative side effects such as headaches and some serious such as kidney damage and kidney failure. The effect isn’t instant.

Question 49

How can an artificial heart be used?

Answer 49

An artificial heart can pump blood around the body. If a patient has a heart failure, doctors may perform a heart transplant using donor organs from those who have recently died. If organs aren’t available then doctors may fit an artificial heart. Artificial hearts are mechanical devices that pump blood to a person whose own heart has failed. They’re usually only a temporary fix until a donor heart can be found but sometimes can be permeant.

The main advantage of artificial heart is that it’s less likely to be rejected by the body’s immune system than a donor heart. This is because they’re made of metals or plastics so the body doesn’t recognise them as foreign and attack in the same way as it does with living tissue

Disadvantages- surgery to fit an artificial heart can lead to bleeding and infection. They don’t work as well as natural ones because parts of the heart could fail such as the electrical motor. Blood also doesn’t flow through as smoothly which can cause blood clots and lead to strokes.

Question 50

Explain how the hearts valves can be replaced

Answer 50

The valves in the heart can be damaged or weakened by heart attacks,infection,old age.

The damage may cause the valve tissue to stiffen, so it won’t open properly. Or the valve will become leaky and allow blood to flow in both directions. This means the blood doesn’t circulate as effectively as normal.

Severe valve damage can be treated by replacing the valve. Replacement valves can be taken from humans or other mammals known as biological valves. Or they are man made-mechanical waves.

Replacing a valve is a major surgery and there can still be problems with blood clots.

Question 51

Explain how artificial blood can keep you alive in an emergency

Answer 51

When someone looses a lot of blood, their heart can still pump the remaining blood cells around as long as the volume of their blood can be topped up. Artificial blood is a blood substitute which is used to replace the lost volume of blood. It’s safe and can keep people alive. It may give the patient enough time to produce new blood cells. Artificial blood will replace the function of the lost red blood cells so there’s no need for a blood transfusion.

Question 52

What is health?

Answer 52

A state of physical and mental wellbeing

Question 53

What is a communicable disease? Give examples

Answer 53

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

Question 54

What is a non-communicable disease? Give examples

Answer 54

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

Question 55

Give examples of diseases that interact

Answer 55

People who have problems with their immune system have an increased chance of suffering from communicable diseases such as influenza because their body is less likely to be able to defend itself against the pathogen that causes disease

Some types of cancer can be triggered by infection by certain viruses. For example infection with some types of hepatitis virus can cause long-term infections in the live, where the virus lives in the cells. This can lead to an increased chance of developing liver cancer.

Mental health issues such as depression can be triggered when someone is suffering from severe physical health problems.

Question 56

Give examples of other factors can also affect your health

Answer 56

Whether or not you have a good,balanced diet that provides your body with everything it needs in the right amounts. A poor diet can affect your physical and mental health.

Stress can lead to health issues

Life situation. Such as access to medicines to treat illness. Being able to buy healthy food. Access to condoms to prevent STI’s

Question 57

What are risk factors?

Answer 57

Risk factors are things that are linked to an increase in the likelihood that a person will develop a certain disease during their lifetime. They don’t guarantee that someone will get the disease.

Question 58

Give examples of some risk factors which can cause a disease directly.

Answer 58

Smoking- has been proven to directly cause cardiovascular disease,lung disease and lung cancer.

Obesity- can directly cause 2 types of making the body less sensitive or resistant to insulin

Alcohol- drinking too much alcohol can cause liver disease and brain function.

Smoking and drinking- when pregnant can cause lots of health problems for the unborn baby.

Cancer- directly caused by exposure to certain substances or radiation . Carcinogens and ionising radiation.

Question 59

What is cancer?

Answer 59

Cancer is the uncontrolled growth and division is a result of the changes that occur in cells and results in the formation of a tumour (a mass of cells).

Not all tumours are cancerous, they can be either benign or malignant

Question 60

What is a benign tumour?

Answer 60

A benign tumour is where a tumour grows until there’s no more room. The tumour stays in one place(usually within the membrane) rather than invading other tissues in the body. This type isn’t normally dangerous and the tumour isn’t cancerous.

Question 61

What is a malignant tumour?

Answer 61

A malignant tumour is where the tumour grows and spreads 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 and elsewhere in the body and form secondary tumours. Malignant tumours are dangerous and can be fatal. They are cancerous.

Question 62

Give examples of some lifestyle factors which can increase the chance of some cancers

Answer 62

Smoking- linked to lung cancer but research shows it to other types of cancer as well

Obesity- linked to cancer. Linked to many different cancers including bowel, liver and kidney.

UV exposure- people exposed to the sun have an increased chance of developing skin cancer.

Viral infection- infections such as hepatitis B and C can increase the risk of developing liver cancer..

Question 63

Give examples of some genetic factors that affect cancer

Answer 63

Sometimes people inherit faulty genes which make them more vulnerable to cancer

Question 64

What are plant cells organised into?

Answer 64

Plant cells are organised into tissues and organs, such as stems, roots and leaves. Plant organs work together to form plant organ systems.

Question 65

What does the epidermal tissue do?

Answer 65

Covers the whole plant

Question 66

What does the palisade mesophyll tissue do?

Answer 66

Where photosynthesis happens

Question 67

What does the spongy mesophyll tissue do?

Answer 67

Contains big air sacs to allow gases to diffuse in and out of cells.

Question 68

What do the xylem and phloem do?

Answer 68

Transport things like water, mineral ions and food around the plant through the stems roots and leaves

Question 69

What does the meristem tissue do?

Answer 69

Found in 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 70

List all the tissues the leaf contains

Answer 70

Epidermal, mesophyll, xylem and phloem tissues

Question 71

Explain the epidermal tissue

Answer 71

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

Question 72

Explain the upper epidermis

Answer 72

The upper epidermis is transparent so that light can pass through it to the palisade layer

Question 73

Explain the palisade layer

Answer 73

The palisade layer has lots of chloroplasts which means that they’re near the top of the leaf where they can get most light

Question 74

Explain the xylem and phloem

Answer 74

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

Question 75

Explain how the tissues of leaves are adapted for efficient gas exchange

Answer 75

The lower epidermis is full of stomata which let co2 diffuse directly into the leaf. The opening and closing of stomata is controlled by guard cells in response to environmental conditions. The air spaces in the spongy mesophyll tissue increase the rate of diffusion of gases

Question 76

Explain the function of Phloem tubes

Answer 76

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

Question 77

Explain the function of xylem tubes

Answer 77

They are 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 78

What is transpiration?

Answer 78

Transpiration is caused by the evaporation and diffusion of water from a plant’s surface. Most of transpiration happens at the leaves. This evaporation creates a slight shortage of water in the leaf and so more water is drawn from the rest of the plant through the xylem vessels to replace it. This means more water is drawn up from the roots and there’s a constant transpiration stream of water through the plant.

Because there’s more water inside the plant than in the air , the water escapes from the leaves through the stomata by diffusion.

Question 79

Give examples of factors that affect the rate of transpiration

Answer 79

Light intensity- The more exposure to light , the greater the transpiration rate. Stomata start to close when it’s darker and photosynthesis can’t happen in the dark. When the stomata are closed very little water can escape

Temperature- The warmer it is the faster transpiration happens. When it’s warm the water particles have more energy to evaporate and diffuse across the stomata.

Air flow- The better the air flow around the leaf the greater the transpiration rate. If there’s good air flow the water vapour is swept away maintaining a low concentration of water in the air outside the leaf. Diffusion then happens.

Humidity- The drier the air around the leaf, the quicker the rate of transpiration. If the air is humid there’s a lot of water in it already. Therefore diffusion won’t happen.

Question 80

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

Answer 80

They have a kidney shape which opens and closes the stomata. When the plant has lots of water the guard cell fills up and goes plump and turgid. This makes the stomata open so gases can be exchanged for photosynthesis. When the plant is short for water the guard cells lose water and become flaccid making the stomata close. This helps to stop too much water vapour from 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. Stomata are more commonly present on the undersides of a leaf because the lower surface is shaded and cooler so less water is lost through the stomata. Guard cells are therefore adapted for gas exchange and controlling water loss within a leaf.