B2 Enzymes And Genetics

Question 0

How does an enzyme work?

Answer 0

All enzymes have unique shape that fits on to a substance.

This means that they only increase one reaction as only one can fit into the unique shape.

Question 1

Explain enzymes.

Answer 1

The chemical reactions in the body have to be sped up.
If the temperature is raised cells will get damaged and unwanted reactions will get sped up.
Enzymes are catalysts that increase the rate of the reactions but aren’t used up or changed.
They are all made of proteins and they all have a unique job.

Question 2

Explain the environment needed for an enzyme to work.

Answer 2

The reaction will increase with heat but should it get too hot the enzyme will denature. They generally work best at 37C.
pH also affects reactions. If it is wrong then the enzyme will denature.
The optimum pH is normally 7. However some (like pepsin) works best at 2.

Question 3

Explain what digestive enzymes do to food molecules.

Answer 3

Starch, proteins and fats are large molecules, so they can’t go through digestive walls.
Sugars, amino acids, glycerol and fatty acids are small enough.
Digestive enzymes break big molecules into smaller ones.

Question 4

Explain the breaking down of starch.

Answer 4

Amylase turns starch into maltose and other sugars.

Amylase is made in the small intestine, pancreas and salivary glands.

Question 5

Explain the breaking down of proteins.

Answer 5

Protease turns proteins into amino acids.

Protease is made in the stomach, pancreas and small intestine.

Question 6

Explain the breaking down of fats.

Answer 6

Fats can also be know as lipids.
Lipase turns lipids into fatty acids and glycerol.
Lipase is made in the pancreas and small intestine.

Question 7

What does bile do?

Answer 7

It is produced in the liver, stored in the gall bladder and used in the small intestine.
This neutralises the hydrochloric acid making it alkaline meaning the enzymes that work there work well.
It also emulsifies fat. This increases the surface area and means the reaction takes place faster.

Question 8

Define respiration.

Answer 8

It is the process of releasing energy from glucose which goes in in every cell.

Question 9

What is the equation for aerobic respiration?

Answer 9

Glucose + oxygen = carbon dioxide + water + energy.

It happens all the time.

Question 10

What is the energy released by respiration used for?

Answer 10

To build larger molecules from smaller ones. E.g. proteins from amino acids.
In animals, to make muscles contract causing movement.
In mammals and birds the energy is used to keep a steady body temperature.
In plants sugars, nitrates and other nutrients are made into amino acids which then become proteins.

Question 11

Explain the role of glycogen in exercise.

Answer 11

Some glucose is stored as glycogen. It is many found in the liver but muscles have their own store.
During vigorous exercise glycogen is turned back into glucose to keep up with demand.

Question 12

Explain anaerobic respiration.

Answer 12

Glucose = energy + lactic acid.
It doesn’t produce as much energy as aerobic respiration.
The lactic acid builds up and this hurts. It causes muscle fatigue and the muscles don’t work as well.
After movement you will still be breathing heavily as your body has to oxidise the acid to get rid of it.

Question 13

How are enzymes used in biological detergents?

Answer 13

They are mainly the fat and protein digesting enzymes ( proteases and lipases)
They break down animal and plant matter so they can clean off food and blood stains.
They are more effective at low temperatures (30C)

Question 14

How are enzymes used in food?

Answer 14

Proteases are used to pre digest proteins in baby food so it is easier for the baby to digest it.
Carbohydrate digesting enzymes can turn starch syrup into sugar syrup.
Glucose syrup can be turned into fructose syrup through the use of an isomerase enzyme. Fructose is sweater meaning less can be used meaning less calories.

Question 15

What are the advantages of using enzymes in industry?

Answer 15

They speed up the reaction so high temperatures and pressures aren’t needed meaning it’s cheaper.
They only speed up the reactions you want them to.
Enzymes work for a long time, they can be used over and over again.
They are biodegradable and cause less pollution.

Question 16

What are the disadvantages of using enzymes in industry?

Answer 16

Some people have allergies to them. They can’t use bio washing powder.
A small change in temperature, pH or poisons can denature them. The conditions have to be controlled
They are expensive to produce.
Contamination of the enzyme can affect the reaction.

Question 17

What is DNA?

Answer 17

It is the instructions to make an organism.

It is found in the nucleus of animal cells , in long molecules called chromosomes.

Question 18

What is DNA finger printing?

Answer 18

A persons DNA is is cut into small sections and separated. This produces a unique pattern.
It is used in paternity tests to see if a man is the farther of a child and in forensic science.

Question 19

Explain Mitosis.

Answer 19

A body cell has 23 pairs of chromosomes. These have to be replicated.
The DNA is copied as the chromosomes copy themselves and they look like Xs with two arms. These arms then split apart and then so does the cell.
It is used in growth, repair and asexual production.

Question 20

How many chromosomes does a gamete have?

Answer 20

23. When two fuse the new cell will have 23 pairs.

Question 21

Explain how meiosis works.

Answer 21

There are two divisions. In the first one ordinarily mitosis happens resulting in tow cells with 23 pairs. However now the pairs are separated and then the chromosomes are split apart the the two cells split again.
This results in 4 cells with 23 chromosomes.

Question 22

Explain stem cells and why they can become any type of cell.

Answer 22

Differentiation is the process where cells become specialised to do a certain job. Older animal cells can’t do this but many plant cells can.
An undifferentiated cell can turn into any type of cell. These are stem cells.
Stem cells can be found in human embryos or in the bone marrow of adults but these aren’t as versatile. They can only become certain types of cells

Question 23

How can stem cells cure diseases?

Answer 23

Those will blood diseases can be treated with bone marrow transplants. The stem cells become new blood cells.
They can be taken from human embryos and can become, heart beating muscle cells, insulin producing cells or nerve cells for those who are paralysed.
Lots of research is needed.

Question 24

Why are some people against stem cell research?

Answer 24

They feel human life shouldn’t be tested on.
Others say living people are more important than cells.
Usually the cells used in this research are unwanted and from fertility clinics. However many people are against this as well.
These people say they should try and find other sources of stem cells.

Question 25

Explain the chromosomes of men and woman.

Answer 25

Men have a X and Y chromosome.

Women have X and X chromosome.

Question 26

What is a fossil?

Answer 26

The remains of an organism from many years ago found in rocks.

Question 27

What are the three ways in which fossils can form?

Answer 27

Casts and impressions, gradual replacement of minerals and preservation where decay can’t happen.

Question 28

How does the gradual replacement of minerals work?

Answer 28

This is the most common type of fossil.
Things like bones and shells that don’t decay easily last along time. These will get replaced by minerals during decay forming rock like substances that take their shape.

Question 29

How do fossils form from casts and impressions?

Answer 29

An animal can be buried in clay or a soft material.
The animal will decay and the material will harden, leaving an animal shaped hole.
A burrow, roots, and footprints can be preserved in this way.

Question 30

Explain how fossils form when they are preserved no can’t decay.

Answer 30

Amber and tarp pits can surround an organism. There is no oxygen or water for decay.
In glaciers it is too cold for decay.
Peat bogs are too acidic for bacteria.

Question 31

What are the hypothesises for the start of life?

Answer 31

They existed in a primordial swamp or in the sea.

Comets might have brought simple organic molecules to earth which later formed more complex molecules.

Question 32

Why is there little evidence for hypothesises about the start of life?

Answer 32

Many think the first organisms were soft bodied meaning they decay and don’t form fossils.
Many old fossils have been destroyed by geological activity.

Question 33

Why do animals become extinct?

Answer 33

The environment changes. ( destruction of habitats)
A new predictor kills them all.
A new disease kills them all.
They can’t compete with a new species for food or other things.
A catastrophic event occurs and they all die. ( volcano or astoroid)
A new species develops.

Question 34

What is speciation?

Answer 34

A species is defined as a group of similar organisms that can reproduce to have fertile offspring.
When a new species comes about it is called speciation.
This happens when members of the same species become so different they can no longer breed.

Question 35

How does isolation and natural selection lead to speciation?

Answer 35

Isolation occurs when a species is separated. A barrier can form because of a flood or earthquake. Conditions on the different sides will be different meaning natural selection will occur.
Individuals with characteristics that make them better adapted will reproduce and the species will change.

Question 36

Explain embryo screening?

Answer 36

During IVF a cell can be removed from an embryo and analysed.
Many genetic disorders like cystic fibrosis can be found in this way.
Embryos with good alleles would be put into the mother.

Question 37

What are the arguments against embryonic screening

Answer 37

It is expensive.
It implies people with genetic problems ate undesirable which is prejudiced.
Rejected embryos are destroyed and they could have become human beings.
They may come a point where all embryos are screened so they can have the most desirable one e.g. Tall, blond ,clever and a boy.

Question 38

What are the reasons for embryonic screening?

Answer 38

It will stop suffering.
Laws stop it going too far. Parents can’t chose the sex.
During IVF, most embryos are destroyed anyway. Screening means the healthy ones go on.
Treating disorders costs the country a lot of money.

Question 39

What does the stomach do?

Answer 39

Mechanical digestion. Pummels food.
Uses hydrochloric acid to dissolve food and kill pathogens.
It also produces a protease called pepsin

Question 40

What does the gall bladder do?

Answer 40

Store bile before it goes into the small intestine.

Question 41

What goes the pancreas do ?

Answer 41

Produces protease, amylase and lipase.

Question 42

What does the small intestine do?

Answer 42

Produces protease, amylase and lipase.

Where digested food is absorbed out of the digestive system.

Question 43

What is an allele?

Answer 43

Different versions of the same gene.

Question 44

What does homozygous mean?

Answer 44

It has two alleles for a particular gene that are the same.

Question 45

What does heterozygous mean?

Answer 45

It is when the two alleles for the same gene are different.