Topic 2 - Organisation

Question 1

What is the order of how cells become organ systems?

Answer 1

Cells - Tissues - Organs - Organ systems

Question 2

What is a catalyst?

Answer 2

Catalyst:

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

Question 3

What is an enzyme?

Answer 3

Enzyme:

— A biological catalyst

Question 4

How does an enzyme work?

Hint: what needs to fit into what for it to work

Answer 4

Each enzyme has an unique active site that only allows a certain substrate to fit into it. Think of it as the ‘lock and key’ diagram. For the enzyme to work, the substrate has to fit into the active site.

Question 5

What is the general optimum temperature and pH that enzymes work best at?
What happens if the optimum conditions are not met?

Answer 5

• – The optimum temperature is 37 degrees and the optimum pH is 7 (neutral).
• – If the temperature gets too hot or pH is too low or too high, then the enzyme can denature. This means that the shape of the active site could change which means the substrate won’t be able to fit into the active site anymore meaning the enzyme won’t work.

Question 6

What big molecules do carbohydrases (e.g. amylase), proteases and lipases break down into smaller molecules?

Answer 6

• – Carbohydrases break down cabohydrates into simple sugars (e.g. amylase breaks down starch to maltose)
• – Proteases break down proteins to amino acids
• – Lipases breaks down lipids into glycerol and fatty acids

Question 7

Where are carbohydrases, proteases and lipases found in the body?

Answer 7

• – Carbohydrases: salivary glands, pancreas, small intestine
• – Proteases: pancreas, stomach, small intestine
• – Lipases: pancreas, small intestine

Question 8

Where is bile produced and stored? What is the role of bile in the body?

Answer 8

Bile is produced in the liver and stored in the gall bladder. The role of bile is to emulsify fats and neutralise stomach acid. The bile breaks the fats into tiny droplets to increase the surface area for the lipases to act on. Also it neutralises stomach acid because the pH of the stomach is 2 which is very acidic so because bile is alkaline, it neutalises the acidic conditions.

Question 9

What side of the heart pumps oxygenated blood and which side pumps deoxygenated blood?

Answer 9

• – Right side: deoxygenated blood

- – Left side: oxygenated blood

Question 10

What do valves do?

Answer 10

Valves prevent backflow of blood in the heart.

Question 11

What are the four chambers of the heart?

Answer 11

Right atrium, right ventricle, left atrium, left ventricle

Question 12

How does the heart pump blood around the body?

Answer 12

Dexoygenated blood flows into the right atrium via the vena cava. The right atrium contracts forcing the blood into the right ventricle which then contracts to force the blood into the pulmonary artery away from the heart and into the lungs where gaseous exchange takes place. The oxygenated blood then enters the left atrium via the pulmonary vein. The left atrium contracts, forcing blood into the left ventricle which then contracts and forces blood out of the heart and to the rest of the body via the aorta.

Question 13

What is the role of a pacemaker and where is it located in the heart?

Answer 13

A pacemaker is a group of cells that control the natural resting heart rate of a person. It is located in the right atrium of the heart. An artificial pacemaker can be used to control an irregular heartbeat.

Question 14

What are the three blood vessels and their functions?

Answer 14

• – Arteries: carry blood away from the heart under a lot of pressure
• – Capillaries: involved in exchanging material at the tissues
• – Veins: carry blood to the heart

Question 15

How does the structure of each blood vessel relate to its function?

Answer 15

• – Arteries: have thick walls that are very strong and elastic as they work under high pressure, the lumen is not very big
• – Capillaries: thin permeable walls that are one cell thick to increase the rate of diffusion of substances and very small lumen
• – Veins: thin walls as they work under low pressure, wide lumen to allow blood to flow under the low pressure, contain valves to prevent backflow of blood

Question 16

What are the main components in blood and their functions?

Answer 16

• – Red blood cells: carry oxygen
• – White blood cells: prevent against infection
• – Platelets: help blood clot
• – Plasma: liquid that carries everything in the blood

Question 17

How are the components of the blood adapted to perform their functions?

Answer 17

• – Red blood cells: biconcave shape for an increased surface area to carry more oxygen, no nucleus provides more room to carry oxygen, red pigment called haemoglobin which binds to oxygen in the lungs to transfer more oxygen around the body
• – White blood cells: changes shape to engulf and digest microorganims (phagocytosis), produces antibodies and antitoxins to counteract the effect of harmful toxins in microorganisms, contains a nucleus.
• – Platelets: small fragments of cells with no nucleus, help blood clot at a wound to prevent excessive bleeding and prevent harmful microorganisms enter the body
• – Plasma: pale straw-coloured liquid that carries RBC, WBC, platelets, nutrients, carbon dioxide, hormones, urea, antibodies and antitoxins

Question 18

What causes coronary heart disease?

Answer 18

When layers of fatty material build up in the coronary ateries which narrow them causing a reduced flow of blood so a lack of oxygen for the heart muscle.

Question 19

How do stents and statins help people with coronary heart disease?

Answer 19

Stents help by keeping the coronary artery open. Statins reduce the amount of bad cholesterol in the blood which reduces the amount of fatty deposits forming in the coronary arteries.

Question 20

What is the effect of faulty heart valves and how can they be replaced?

Answer 20

A faulty valve means a valve cannot open or might leak which will allow blood to flow in both directions. It can be replaced using a biological or mechanical valve.

Question 21

What could happen in the event of heart failure?

Answer 21

• – An articifcial heart can be implanted to help pump blood around the body while waiting for a transplant or give the heart a break from pumping to aid its recovery
• – Heart transplant (maybe lung too if needed)

Question 22

What are risks and benefits of an artificial heart?

Answer 22

Benefit:
— Less likely to be rejected as it is not seen as ‘foreign’

Risks:

• – Can cause bleeding or infection
• – Wears out or electrical motor could fail
• – Patient has to take drugs to thin the blood to prevent blood clots

Question 23

What is health?

Answer 23

Health is the state of physical and mental well-being.

Question 24

What are four examples of when diseases can interact with each other?

Answer 24

• – A weak immune system makes it harder for the body to fight infectious diseases and give a higher chance of catching communicable diseases.
• – Viruses living in cells can trigger cancers.
• – Immune system reactions caused by pathogens can trigger allergies such as skin rashes or asthma.
• – Severe physical illnesses can lead to depression and other mental health conditions.

Question 25

What are factors that have an effect on health?

Answer 25

• – Diet
• – Stress
• – Life situations e.g. access to medicines or things that prevent illnesses

Question 26

What are five risk factors that can cause a disease directly?

Answer 26

• – Smoking causes cardiovascular disease, lung disease and lung cancer.
• – Obesity is linked to type 2 diabetes.
• – Alcohol and smoking can cause health problems for an unborn baby.
• – Carcinogens (radiation etc.) can be directly linked to cancer.
• – Alcohol can cause liver disease and affect brain function.

Question 27

What causes cancer?

Answer 27

Uncontrolled growth and division as a result of cell changes

Question 28

What are the types of tumors and explain them?

Answer 28

• – Benign: not cancerous, does not spread to other parts of the body
• – Malignant: spreads to other parts of the body via the bloodstream by invading other cells, cancerous and can be dangerous

Question 29

How are the plant tissues related to their function?

Answer 29

• – Epidermal tissues: covered in waxy cuticle to reduce water loss
• – Upper epidermis: transparent to allow light pass through to palisade layer for photosynthesis
• – Palisade mesophyll: contain lots of chloroplasts for photosynthesis
• – Spongy mesophyll: air spaces to increase rate of diffusion
• – Xylem and phloem: transport water and nutrients around plant
• – Meristem tissue: found at growing tips of shoots and roots to allow plant to grow by differentiating into different plant cells.

Question 30

What is the role of phloem and xylem?

Answer 30

• – Phloem: to transport food and nutrients around the plant by translocation via columns of living cells
• – Xylem: to transport water and mineral ions from the roots up the plant and out the leaves by transpiration via dead cells joined end to end

Question 31

What is the role of stomata and guard cells?

Answer 31

Control gas exchange and water loss

Question 32

Describe the transpiration stream

Answer 32

Water diffuses and evaporates out the plant’s surface (usually the leaves) which causes a water shortage in the plant so more water is pulled up the roots via the xylem vessels.

Question 33

What four things affect rate of transpiration? Explain each

Answer 33

• – Light intensity: the brighter the light, the greater rate of transpiration
• – Temperature: the warmer it is, the greater rate of transpiration
• – Air movement: better air flow, greater rate of transpiration
• – Humidity: the drier the air, greater rate of transpiration