Assesment B1 Revision

Question 1

The difference between prokaryotic and eukaryotic cells

Answer 1

Eukaryote cells are complex and include animal and plant cells, prokaryotic cells are smaller and simpler e.g bacteria

Question 2

Define each cell function

Answer 2

Nucleus- contains DNA, controls the activity
Cytoplasm- chemical reactions take place, contains enzymes
Cell membrane- controls movement and holds it together
Mitochondria- used for respiration, transfers energy
Ribosomes- where proteins are made

Question 3

What is the equation for magnification?

Answer 3

Top: image size
Left: magnification
Right: real size

Question 4

Why are there specialised cells?

Answer 4

For reproduction, rapid signaling, contraction, absorbing water and minerals and transporting substances

Question 5

What is mitosis?

Answer 5

When the chromosomes line up in the center or the cell, cell fibres pull them apart, the two arms of each chromosome go to the opposite ends of each cell. Cell membranes form around each set of chromosomes, these become the nuclei of the cell then the cytoplasm and cell membrane divide making two new daughter cells

Question 6

What is differentiation?

Answer 6

When a cell changes to become a specialised cell to carry out a new process

Question 7

Stem cells are found in the…

Answer 7

Meristem/ bone marrow (where growth happens)

Question 8

What is osmosis?

Answer 8

The movement of water across a partially permeable membrane by by diffusion

Question 9

What happens to the water in an osmosis experiment?

Answer 9

If the cylinders draw in water they will have increased in mass, if it’s drawn out then it’s decreased in mass

Question 10

What is active transport?

Answer 10

It allows the plant to absorb minerals from a very dilute solution against the concentration gradient. This process requires energy from respiration to work. E.g taking in glucose from the gut

Question 11

What are enzymes?

Answer 11

• They act as biological catalysts,
• they reduce the need for high temperature
• they speed up useful chemical reactions in the body.
• Every enzyme has an active. made up of chains of amino acids which are folded into unique shapes to carry out their job
• if the substrate does fit it’s active site it won’t be a catalyst reaction

Question 12

What is a catalyst?

Answer 12

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

Question 13

State what happens in a catalyst reaction

Answer 13

• The substrate binds to the active site to fer an ‘induced fit’
• they have an optimum temperature for the enzyme-catalyst reaction which is normally 0-45°
• If it’s too hot the bonds in the enzyme break, its denatured
• they also have an optimum pH normally 7 unlike pepsin which breaks down stomach acid and works best at pH2

Question 14

What are each tests?

Answer 14

Benedict’s: sugars blue to green. Yellow to brick red
Iodine: starch blue black
Biuret: proteins blue to pink or purple
Sudan III: lipids bright red

Question 15

What is the amylase?

Answer 15

It is an example of a carbohydrase, it breaks down starch and it’s found in the salivary glands, the pancreas and the small intestine

Question 16

What are proteases?

Answer 16

They convert proteins into amino acids which are found in the stomach (called pepsin there), the pancreas and small intestine

Question 17

What are lipases?

Answer 17

They convert lipids (fats and oils) into glycerol and fatty acids and are made in the pancreas and the small intestine

Question 18

What is bile?

Answer 18

It’s produced in the liver and stored in the gall bladder before being released into the small intestine. The hydrochloric acid in the stomach is too acidic in the stomach for the enzymes in the small intestine to work properly. So bile is alkaline which neutralisés the acid. It emulsifies fats (breaks down) this gives the enzyme a large surface area for it to work on making digestion faster

Question 19

State each function of the catalyst reactions

Answer 19

Salivary glands: produce amylase enzymes in the saliva
Liver: where bile is produced
Gall bladder: where bile is stored
Large intestine: where excess water is absorbed from food
Small intestine: produces protease, amylase and lipase for digestion
Pancreas- produces protease, amylase and lipase
Stomach- produces protease and pepsin and hydrochloric acid to kill bacteria and give the pH2 for protease to work

Question 20

What is gas exchange?

Answer 20

The lungs contain alveoli, surrounded by a network of blood capillaries where gas exchange happens. The blood passing next to the alveoli contains a lot of carbon dioxide from the lungs. Oxygen diffusés out the alveolus into the blood then the carbon dioxide diffuses into the blood

Question 21

What happens in the lungs?

Answer 21

The air goes through the trachea then splits into two tubes called bronchi going to each lung. Which then splits into even smaller tubes called bronchioles. It ends at a small bag called alveoli where gas exchange happens.

Question 22

What’s the types of blood vessels?

Answer 22

Arteries: carry the blood AWAY from the heart
Veins: carry the blood to the heart
Capillaires: involved in the exchange of materials at the tissues
Arteries branch into capillaries

Question 23

What is plasma?

Answer 23

It’s the liquid that carries everything in blood

• Carbon dioxide: from the organs to the lungs
• Urea: from the liver to the kidneys
• Hormones
• Proteins
• Antibodies and antitoxins

Question 24

What are the pros and cons of statins reducing high cholesterol?

Answer 24

It reduces the risk of stokes, coronary heart disease and heart attacks. It increases HDL cholesterol, statins also help prevent other diseases.
-Statins must be taken regularly so there’s the risk someone might forget
Negative side effects like headaches, kidney failure, liver damage and memory loss. Statins aren’t instant effect