Year 9 Cell Organisation Answers

Part 1: Tissues and organs

1. Complete the table (one row has been completed for you)

Organisational

levels Definition Example

Cell Building blocks of

life. From Latin

‘cella’, meaning "small

room".

Sperm, muscle,

egg, root hair cell,

nerve, epithelial

cell. And many

more.

Tissue

A group of

specialised cells the

perform the same

function

Muscle

Organ When more than one

tissue is working

together to

complete a specific

function.

Stomach, brain,

pancreas…many

others

System (Organ) These organ systems

are made up of many

organs.

Digestive system,

immune system,

nervous system,

reproductive

system, and more…

Organism Made up of organ

systems. It is a

multi-cellular living

thing.

Human, daisy,

mushroom, lizard,

frog… so many

more.

2. The stomach contains mainly three types of tissues. State their functions.

a.) Muscular tissue. This tissue contracts and relaxes. It churns up the food with the

stomach acid and protease enzymes.

b.) Glandular tissue. This produces the digestive juices including the stomach acid and

the protease enzymes.

c.) Epithelial tissue. It covers the stomach (like a layer of skin).

3. Decide for each of the following if they are a specialised cell, tissue or organ. Explain

and state their functions.

a.) Pancreas. This is an organ (gland) that produces digestive enzymes (proteins) and

regulates blood glucose producing hormones. It produces all 3 types of digestive

Increasing

size

Increasing

complexity

enzymes: lipase, protease and carbohydrase. The two hormones for regulating blood

glucose are called insulin and Glucagon.

b.) Neurone. This is a cell. It passes electrical impulses along its axon and from cell to

cell.

c.) Lungs. Organs. They are responsible for gas exchange. Oxygen from the alveoli in

the lungs to the red blood cells in the capillaries via diffusion. And carbon dioxide

from the plasma in the capillaries into the alveoli of the lungs (again by diffusion)

and then excreted.

4. Matt says “The skin is an organ because it is made from epithelial, muscle and

glandular tissue.” Is he correct? Give a reason.

Matt is correct. The skin is composed of two main layers: the epidermis, made of

closely packed epithelial cells (tissue), and the dermis, made of dense,

irregular connective tissue that contains blood vessels, hair follicles, sweat glands

(glandular tissue), muscle tissue and other structures.

Part 2- The digestive system

1. Label the digestive system with each organ and their function.

Mouth – tongue and teeth.

Mechanical digestion. Cutting up the

food decreasing the surface area and

moving it around to mix with the

saliva.

Salivary Glands – Produces saliva which

contains the enzyme amylase which

carries out chemical digestion. This breaks

down large insoluble starch molecules

into smaller soluble glucose molecules.

Oesophagus – muscular tube that moves

food and saliva from the mouth to the

stomach via peristalsis

Stomach – Contains stomach acid (pH 2) to kill

pathogens, muscular bag that churns up and

mixes the food with the digestive juices

(mechanical digestion) and releases protease

enzymes to breakdown protein into amino acids.

Pancreas – Makes and releases enzymes

(biological catalysts) that break down

large insoluble molecules into small

soluble molecules. Enzymes are proteins

and this is chemical digestion. The

pancreas makes lipases, carbohydrases

and proteases.

Liver – produces bile which is then releases

into the gall bladder for storage until it is

needed in the small intestines. Bile has two

jobs and is involved in chemical digestion.

It emulsifies lipids (fats and oils) and

neutralises the stomach acid. This helps

lipase digest lipids.

Gall Bladder – stores bile

made in the liver and

releases this into the small

intestines when needed.

Small Intestines –

This is where all

three types of

digestive enzymes

work. Lipase,

protease and

carbohydrase

released from the

pancreas and bile

from the liver

enters here.

Lipase breaks

down lipids into

fatty acids and

glycerol.

Carbohydrase

(amylase) breaks

down starch and

other

carbohydrates

into sugars.

Large intestines- Water is

reabsorbed into the blood

steam here.

Rectum – storage of solid waste (faeces)

Anus – Where faeces exits the body.

Protease breaks down

proteins into amino acids.

2. Summarise the information above in the flow chart below

3. What is digestion? The breakdown of large insoluble food molecules into small water-

soluble food molecules so that they can be absorbed into the blood.

4. Why is digestion important to us? Without digestion we would not be able to carry out

essential reactions. We require these small soluble molecules for many of these. One

such reaction is respiration which requires glucose from our small intestines.

Saliva – amylase to break down starch into sugar

(chemical digestion). Mechanical digestion – teeth

and tongue.

Rectum and Anus – Storage of faeces in the rectum

before the ring of muscle allows faeces to exit the

body via the anus.

Removal of excess water. Reabsorbed into the

blood here.

All three enzymes (chemical digestion) from

pancreas. Lipase – digests lipids into fatty acids and

glycerol, Protease – digests proteins into amino

acids. And Carbohydrase (amylase) digests

carbohydrates into sugars. Bile from liver (action is

written in the Liver box.

Produces all three digestive enzymes. Lipase,

carbohydrase and protease.

Stores bile before release into the small intestines.

Protease enzyme for protein digestion into amino

acids (chemical). Stomach acid pH2 to kill

pathogens. Mechanical digestion – muscular bag

churn and mix.

Oesophagus

Produces bile – Bile neutralises stomach acid and

emulsifies lipids for digestion.

Moves food from mouth to stomach in a muscular

tube by peristalsis.

Liver

Large Intestines

Small Intestines Pancreas

5. Explain why the digestive system is an organ system. An organs system is one that is

made up of several organs which contain different cells work towards performing the

same function.

6. Define ‘emulsify’? This makes then almost water soluble. It holds them in much smaller

droplets so lipase can access a greater surface area of the fats.

7. Complete the sentence below

The small intestine is long and has a high surface area because…the small intestines

is where smaller soluble molecules are absorbed and the greater the surface the

area the more absorption via diffusion and active transport can take place.

8. What is the role of saliva in the mouth? Saliva contains the enzyme amylase that can

breakdown starch into sugar (glucose eventually).

9. When someone has diarrhoea, they have watery stools when they go to the toilet.

What part of the digestive system is most likely not working? Explain your answer.

The large intestines. This is because the excess water is not being reabsorbed and

results in watery stool.

10. What is the name of the organelle where respiration occurs? Mitochondria.

11. After a meal there is a high concentration of amino acids in the small intestine. Which

process will cause them to move into the bloodstream? Explain your answer. Diffusion

– which is a passive transport. Substances move from an area of high concentration to

an area of low concentration. In this case from the small intestines into our

bloodstream.

12. What is the name of the process by which water is absorbed by the large intestine?

Osmosis

13. Why does bile improve the digestion of lipids (fats)? It increases the pH of the

contents coming from the stomach (neutralises it) so that the enzyme lipase can work

and it emulsifies the lipids so the enzyme can come into contact with the surface of

the fats for them to be digested.

14. The picture to the right shows a villus. Explain how they are adapted to absorb

nutrients as quickly as possible. They have an increased surface area due to the

microvilli for diffusion and active

transport of substances to occur

moving them into the blood

efficiently. They have a very rich

blood supply as capillaries run

inside of each villi. They have a

very thin lining to make transport

across this from the small

intestines into the capillaries

easier. They also have many

mitochondria to release energy for

active transport of glucose.

Part 3- The chemistry of food

1. Complete the table below (again if you cannot print you can copy out the table).

Use the information in part 2 to help you.

Nutrient Made of Enzyme that

breaks it down.

Broken down

into?

Uses in living

organisms

Sources in our

diet

Carbohydrate

Carbon,

hydrogen and

oxygen

Carbohydrase -

amylase

Sugars – glucose

Energy store –

respiration.

Pasta, bread,

potatoes

Lipids (Fats)

Carbon,

hydrogen and

oxygen

Lipase Glycerol and

fatty acids Energy store, part

of cell membrane

Dairy, olive oil,

veg oil,

Protein

Carbon,

hydrogen,

oxygen and

nitrogen

Protease Amino acids Repair and grow.

New proteins:

tissues, hormones

and enzymes.

Meat, fish, diary

2. Glucose is absorbed by the small intestines no matter how low its concentration in

the digested food. Which transport mechanism is used in this case? Active

transport

3. State the chemical formula of glucose. C6H12O6.

4. What is the function of the cell membrane? To control the movement of

substances into and out of the cell.

5. What process causes water to move across the cell membrane from a dilute

solution to a concentrated one? Osmosis

6. If a protein shake is 250g in total advertises it is 40% protein how much protein

is in the shake? 40% of 250g = 100g of protein.

7. Whole milk is 4% protein. What mass of whole milk would need to be consumed to

get the same amount of protein as in the protein shake? 40% is 10 times as

much protein in a shake than in whole milk so you would need 10 x 250g = 2500g

of milk is need to get 100g protein.

8. Describe the method for each food test.

• State the reagent.

• Apparatus used.

• Any colour change and the results expected of each test.

Sugar – use benedicts solution (blue). Mix 3-4 drops of benedicts solution with the food

(in water). Place the test tube in a water bath. Heat for 5 mins at 80oC or more and

observe any colour change. It will go green-yellow-orange-red. The more red the more

sugar there is.

Starch – use iodine (brownish). Add the iodine to food in water in a test tube and

observe a colour change if starch is present. It will go blue/black.

Protein – use Biruets solution (blue). Use a pipette to add 1cm3 of the solution to the

food mixture in a test-tube. Shake gently and then leave for a couple of minutes.

Observe a colour change. If it goes pinkish purple, then protein is present.

Fats/Lipids – Use Sudan III or ethanol. Add to the food substance. If you get a layer

of red floating on the top you have fats. This is the test used in AQ

Part 4 Enzymes

1. Match the following keywords with their functions.

2. Name the types of enzymes that catalyse the breakdown of:

a.) Carbohydrates Carbohydrase (amylase)

b.) Lipids Lipase

c.) Proteins Protease

3. Which organs in the digestive system produce digestive enzymes?

Salivary glands, stomach, small intestines and pancreas.

4. Catalase is an enzyme that speeds up the breakdown of hydrogen

peroxide. The enzyme increases the rate of reaction so it is 700 times

faster. If the enzyme reaction took 1.9s how long would the reaction take

if there was no enzyme? Convert the answer to minutes. Give your answer

to 4sf. 1.9s x 700 = 1330 seconds in minutes/ 60 = 22.1666666666 =

22.17 minutes to 4sf.

Catalyst • The enzyme and substrate

bound together.

Enzyme

• The special site in the

structure of an enzyme

where the substrate binds.

Enzyme-substrate complex • The energy needed for a

chemical reaction to take

place.

Activation energy • A substance which changes

the rate of a chemical

reaction without being

changed itself.

Active site • A biological catalyst.

Part 5 Factors affecting enzyme action

1. What does denatured mean? It loses its shape, the active site can no

longer bind to the substrate and no enzyme-substrate complexes are

formed.

2. What happens to enzymes when the temperature is:

a.) Too low There is less kinetic energy within the

particles so the rate of reaction is slower

b.) Too high They denature.

3. Explain the effects of temperature on enzyme

action. As above when the temperature is too low

the enzymes and substrate have less kinetic energy

which results in less collisions and colliding with less

energy so less reactions. When the temperature

goes above 41oC the enzymes start to denature.

They change shape of their active site so cannot

form the enzyme substrate complex and the

substrate cannot be broken down so the rate of reaction drops to zero

(no products formed).

4. What is the optimum temperature for enzymes in the human body? 37oC

5. How does a change in pH cause enzymes to denature? This means that

the forces that hold the enzyme together are weakened and the active

site can change shape preventing the formation of enzyme-substrate

complexes.

6. Using the graph given, calculate the rate of reaction of the enzyme.

Remember to include units. Amount of product formed (g)/ Time (mins)

= Rate of Reaction (g/min). 10.4g/2mins = 5.2g/mins. In g/s you convert

2 mins to seconds first and get 120seconds so 10.4g/120s = 0.0866666

= 0.087 g/s to 2sf.

7. What is pepsin? It is a protease enzyme.

8. What are two differences between pepsin and pancreatic amylase?

Firstly, pepsin and amylase breakdown different molecules. Pepsin

breaks down protein and amylase breaks down starch. Secondly, Pepsin

isn’t made by the pancreas whereas amylase is. Thirdly, pepsin is

adapted to work in a low pH (stomach acid). Amylase isn’t and would

denature at that pH.

9. What is the difference between pepsin and proteases produced by the

pancreas? Pepsin is adapted to work in a low pH (stomach acid) and

proteases are not and work in more neutral pHs.

10. How is the stomach adapted to protect itself from pepsin and the

hydrochloric acid? The stomach produces a thick layer of mucus which

coats your stomach and prevents the hydrochloric acid from digesting

the walls of the stomach.

11. Suggest the optimum pH for enzymes to work in the small intestine.

Enzymes prefer an alkaline pH. pH 7-8 would be acceptable as an

answer.

12. Suggest the optimum pH for enzymes to work in the stomach. The pH of

the stomach ranges from pH 1.5 – 3.5. Optimum pH is around 2

13. Is it correct to say “the stomach produces hydrochloric acid to digest

food”? Explain your answer. This depends. You could say no as the

primary function of the stomach acid is to kill microbes. Yes as it does

provide the ideal pH for the action of the pepsin enzyme which breaks

down protein into amino acids for absorption later into the blood.

14. Is it correct to say “bile breaks down lipids to glycerol and fatty acids”?

Explain your answer. Again, you could take this two ways, but bile

doesn’t break down the lipids into glycerol and fatty acids itself. It just

emulsifies the lipids and neutralises the stomach acid so that the lipase

enzyme can function which does breakdown the lipids. Bile helps but

doesn’t actually breakdown the lipids into their component parts.

15. The graph shows the effect of pH on the activities of three

enzymes, X, Y and Z.

These enzymes help to digest

food in the human digestive

system.

Each enzyme is produced by a

different part of the

digestive system.

a) What is the optimum

(best) pH for the action

of enzyme Z? 8.6 (see

line drawn on the graph

and scale of x axis)

b) The stomach makes a substance that gives the correct pH for

enzyme action in the human stomach. Name this substance

pH

c) Which enzyme, X, Y or Z, will work best in the human stomach?

Circled on the graph the pH 2. Read off the graph the enzyme

that works at its optimum near this pH which is X.

Part 6 The Blood

Blood has four main components: red blood cells, white blood cells, platelets all

of which are carried in a fluid called plasma. Below is a link to a clip about blood

components.

https://www.youtube.com/watch?v=nc_kbfjhiUo

1. Use the above video clip to complete the diagram below to summarise the

constituents of the blood. Ensure you describe any adaptations for each

component.

Plasma is a straw-coloured liquid making up 55% of our blood. Within the plasma

dissolved substances like glucose plus other products of digestion, urea and carbon

dioxide will also be carried.

Red blood cells carry the oxygen from the air in our lungs to our respiring cells. Red blood cells have

certain adaptations that make them efficient at their job. They are biconcave disks which increases

their surface area to volume ratio which increase diffusion. They are packed with haemoglobin which

binds to oxygen. They also have no nucleus which makes space for more haemoglobin.

White blood cells form part of the immune system. Some white blood cells (lymphocytes) produce

antibodies whilst others produce antitoxins and yet others (phagocytes) engulf and digest invading

microorganisms. They can have multi-lobed nuclei and contain many ribosomes to make the antibodies.

Platelets are small fragments of cells without a nucleus. They are involved in the clotting of blood.

Blood clotting is a series of enzyme-controlled reactions that results in the conversion of fibrinogen

into fibrin. This forms a network of fibres that traps more platelets and red blood cells forming a

scan which protects the new skin as it grows.

Part 7 – The blood vessels

Blood is carried round our body in three main types of vessel. Each vessel is

adapted for a different function.

Arteries carry blood away from the heart to the organs or body. The blood is

usually oxygenated with the exception of the pulmonary artery. Blood in the

arteries is under high pressure. Arteries have a thick layer of muscle and

elastic fibres along with thick walls to allow them to withstand the high

pressure and to stretch. Arteries have a small lumen.

Veins carry blood away from organs towards the heart. The blood is low in

oxygen, except for the pulmonary vein. veins have a larger lumen and relatively

thin muscular and elastic walls. This is because the blood is under less pressure.

Veins have valves to prevent blood flowing backwards.

Capillaries connect arteries to veins. Capillaries are very narrow with thin walls.

This ensures there is a short diffusion distance the inside of the capillary and

surrounding cells. This enables substances such as glucose and oxygen to easily

diffuse out of your blood into cells. Conversely carbon dioxide can easily do the

opposite. Capillaries have very narrow lumens which only allow 1 cell to pass

through at a time and their walls are only 1 cell thick.

https://www.youtube.com/watch?v=Wx-MrhlOFMk

1. Complete the labels in the diagram using the text above and the video

clip.

Capillary

Artery Vein

Deoxygenated Blood

Valve

Lumen

Oxygenated blood

Smooth Muscle and elastic

fibres

Fibrous outer layer

Endothelium

Humans have a double circulation system.

One transport system carries blood from

your heart to the lungs and back again

and the other system carries blood from

the heart to all other organs of your

body and back again. This double

circulation system is advantageous to us

as we need lots of oxygen and glucose

transported round our body. The double

circulation system allows lots of

oxygenated blood to be transported

quickly where it needs to go.

2. Why do the arteries have a thick layer of elastic fibres and muscle

tissue? To withstand the blood at high pressure from the heart.

3. What is the pressure like inside the arteries? Very high.

4. What do veins have that prevent back flow? Valves

5. How is the pulmonary vein different to other veins? Pulmonary vein

contains oxygenated blood.

6. What process will allow oxygen to move from the red blood cells into the

muscle cells. Diffusion.

7. Why is our circulation system described as a double circulation system?

It has two separate circuits and blood passes through the heart twice:

the pulmonary circuit is between the

heart and lungs, and the systemic circuit

is between the heart and the other

organs.

8. What is the benefit of the walls of

capillaries only being 1 cell thick?

Decreases the distance that substances

have to diffuse across making this

easier.

9. Name the types of blood vessel labelled

A, B and C on the diagram. A-Arteries,

B-Capillaries and C-Veins

10. Give two ways that the composition of

the blood changes as it flows through the

blood vessels labelled x on the diagram.

The blood before X is low in oxygen and

high is carbon dioxide. Once it travels

through the capillaries at X the blood has a high level of oxygen and

lower levels of carbon dioxide.

11. In the diagram you can see three blood vessels. These are drawn to

scale (see the square brackets next to each one).

b)a Name each of the blood

vessels.

A-Vein, B-Capillary, C-Artery

b)b What is the function of the

blood in diagram B? For

exchange of substances from

body cells to blood or vice versa.

Part 8- The Heart

https://www.youtube.com/watch?v=bpYaKM2hVFY

Right Atrium – top chamber of

the heart, contains

deoxygenated blood returning

from the body

Left Ventricle – top chamber

of the heart, contains

deoxygenated blood returning

from the body

Aorta – Largest blood vessel

with thickest wall. Carries

oxygenated blood away from

the heart at high pressure to

the rest of the body.

Pulmonary Artery – only

artery carrying deoxygenated

blood. Carries blood away

from the heart to the lungs.

Right Ventricle – lower chamber of

the heart, contains deoxygenated

blood which will be sent to the lungs.

The muscle here is thinner than the

left side as blood doesn’t travel far.

Left Atrium – top chamber of

the heart, contains

oxygenated blood returning

from the lungs

Pulmonary Vein – Vein

carrying oxygenated blood

(only one) returning blood to

the heart to be sent to body

cells.

In the capillaries gases are exchanged

with body cells by diffusion and

glucose moves into the cells. Urea

moves out and some water.

Where gas exchange occurs. CO2 out of the

blood into the alveoli and oxygen into the

blood from the alveoli.

A vein carrying deoxygenated

blood from the body back to

the heart.

3. What is the name of the blood vessels that supply the heart with oxygen?

Coronary artery

4. What is the name given to the top chambers of the heart? Atria

5. What blood vessel supplies the left atrium with blood? Pulmonary vein

6. What blood vessel supplies the right atrium with blood? Vena cava

7. What is special about the pulmonary artery? It contains deoxygenated

blood whereas other arteries contain oxygenated blood

8. What type of blood is found in the right ventricle? Deoxygenated blood

9. What causes coronary heart disease? Coronary heart disease is caused by

a build up of fatty deposits that narrow the blood vessel reducing blood

flow and in turn oxygen to the heart muscle. This can lead to a heart

attack (little oxygen for respiration).

10. What are three methods of treating coronary heart disease? Coronary

heart disease can be treated with a stent. A stent is a metal mesh placed

in the artery to open it up. Bypass surgery where the blocked artery is

replaced with bits of veins. Another option is to prescribe statins. Statins

reduce blood cholesterol levels and slows down the rate at which fatty

material is deposited.

11. Why does the left ventricle have thick muscular walls? To provide the

force required to push the blood all around the body.

12. What is an advantage of stents? Stents don’t require general anaesthetic

and can be placed anywhere in the body.

13. How do stents work? A tiny balloon is then inflated to open the blood

vessel and the stent. The balloon is then removed but the stent ensures

the blood vessel remains widened. The stent is a wire mesh that can open

up the blood vessel.

14. Describe the journey of an oxygen molecule from the air into a muscle

cell. Try to include the names of all the organs and cells involved. This can

be sent to your teacher for

marking.

15. Diagram 1 shows a section

through the heart. Name the

parts labelled A, B, C and D.

A-Aorta, B-Left Ventricle,

C-Right Atrium, D-Vena Cava

Part 9 - Breathing and gas exchange

1. What protects your lungs? You rib cage and intercoastal muscles.

2. What makes red blood cells special? Their biconcave shape and lack of

nucleus. They also have a special protein called haemoglobin to which

oxygen attaches.

3. What structure makes up the lungs? Trachea, Bronchi, Bronchioles, alveoli

4. Give two adaptations of alveoli. Large surface area, one cell thick and a

good blood supply (net of capillaries)

5. State two gasses that are moved in and out of the lungs by ventilation.

Oxygen and carbon dioxide are moved in and out (you could state any of

the main gases in air as does not state exchanged).

6. What two sets of muscles control gas exchange. Intercoastal muscles and

the diaphragm.

7. What is the relationship between volume of the chest and pressure? As

the volume increases the pressure inside the chest decreases. And vice

versa.

8. Describe the changes that will occur in the lungs when breathing in and

out. Breathing in: Ribs move up and out (intercoastal muscles control this).

The diaphragm moves downwards (flattens out). The volume of the chest

increases so the pressure decreases. The higher pressure outside causes

air to move into the lungs.

Breathing out: Ribs move down and in (intercoastal muscles control this).

The diaphragm moves upwards. The volume of the chest decreases so the

pressure increases. The lower pressure outside causes air to move out of

the lungs.

9. If the pressure in the lung is high, am I breathing in or out? Out

10. Label the table below with % of air breathed in and % of air breathed out

Atmosphere gas % of air breathed out % of air breathed in

Nitrogen 80 80

Oxygen 16 20

Carbon dioxide 4 0.04

11. a) Draw a bar chart to show the difference between the air you breathe

in and the air you breathe out (use table above). X axis is the gases two

bars side by side for each gas. A key to shade % of air breathed in and %

of air breath ed out. The y axis should go up to 80% and scale should be

the same for each %. Both axis labelled and accurately drawn. This can be

on lined paper if necessary.

b) Describe the changes in the composition gases in inhaled air and

exhaled air. (include magnitude of any difference). This does not require

an explanation! Nitrogen does not change. Oxygen in inhaled air is 20% and

decreases by 4% when exhaled to 16%. Carbon dioxide in inhaled air is just

0.04% and increases in exhaled air to 4%. This is an increase of 3.96%.

c) A student says “we breathe in oxygen and breathe out carbon dioxide”

explain whether the student is correct. Use data from table 1. The

student is not correct. We inhale more oxygen than we exhale, and we

inhale less carbon dioxide than we exhale. Not all the oxygen is removed

from inhaled air, only 4% so there is still 16% exhaled. There is carbon

dioxide in exhaled air as well as inhaled air.