B2b

Question 1

What are enzymes?

Answer 1

Biological catalysts that increase speed of a reaction without being used up. They only catalyse one reaction

Question 2

What are enzymes made from?

Answer 2

Proteins from amino acids in a unique shape

Question 3

Why do enzymes need the right conditions?

Answer 3

Wrong temperature or pH breaks bonds so substrate can’t fit in active site, reaction won’t be catalysed (denatured)

Question 4

What are often the right conditions for enzymes in the human body?

Answer 4

37 degrees

pH7

Question 5

Why do nutrients need to be digested?

Answer 5

Starch, protein, lipids are big molecules but only small molecules can pass through digestive system walls

Question 6

What does amylase do and where is it found?

Answer 6

Starch into glucose/ maltose

Mouth, salivary gland, pancreas, small intestine

Question 7

What does lipase do and where is it found?

Answer 7

Lipids into glycerol + fatty acids

Pancreas, small intestine

Question 8

What does protease do and where is it found?

Answer 8

Proteins into amino acids

Stomach (pepsin), pancreas, small intestine

Question 9

What does the liver do?

Answer 9

Produces bile which neutralises stomach acid (which kills bacteria) and emulsifies fats

Question 10

What do the small and big intestines absorb?

Answer 10

Small - food

Big - water

Question 11

How do biological detergents work?

Answer 11

Proteases + lipases remove stains like food

They work at lower temperatures

Question 12

How are enzymes used in food?

Answer 12

Protease - pre-digested baby food
Amylase - starch into sugar syrup
Isomerase - glucose into fructose

Question 13

What are the advantages of using enzymes in industry?

Answer 13

Specific
Lowers temps and pressure - save money
Last a long time
Biodegradable

Question 14

What are the disadvantages of using enzymes in industry?

Answer 14

Develop allergies
Conditions must be controlled
Expensive
Contaminations

Question 15

What is respiration?

Answer 15

The release of energy from glucose that happens in every cell, in the mitochondria

Question 16

What is the equation for aerobic respiration?

Answer 16

Glucose + oxygen into carbon dioxide + water + energy

Question 17

What is energy used for in plants and animals?

Answer 17

Building larger molecules e.g. proteins
Muscle contraction (mammals)
Maintaining body temp (mammals + birds)
Build sugars, nitrates to amino acids (plants)

Question 18

What happens during exercise?

Answer 18

Muscles need more energy
Extra CO2 needs to be removed
Glycogen in every cell converted to glucose

Question 19

What is anaerobic respiration?

Answer 19

The incomplete breakdown of glucose

Glucose into lactic acid + energy

Question 20

Why can’t anaerobic respiration be maintained for a long time?

Answer 20

Lactic acid build up is painful + muscle fatigue

Doesn’t release as much energy

Question 21

What is oxygen debt?

Answer 21

When your body needs to repay the oxygen not used in exercise
O oxidises lactic acid into CO2 and water

Question 22

What is DNA?

Answer 22

Deoxyribonucleic acid - contains instructions to put organisms together and how they work

Question 23

What is a gene?

Answer 23

A short section of DNA

Question 24

How do genes make proteins?

Answer 24

By determining the order of bases (A,C,G,T). Three bases make one amino acid, which make up proteins. The type of protein made determines the type of cell something is

Question 25

What is an allele?

Answer 25

A different version of the same gene

Question 26

What can DNA fingerprinting be used for?

Answer 26

Forensic science | Paternity tests

Question 27

Describe the process of mitosis

Answer 27

Parent cell replicates DNA making X-shaped chromosomes Chromosomes line up Cell pulled apart to make two daughter cells

Question 28

Describe the process of meiosis

Answer 28

A cell replicates DNA, making X-shaped chromosomes that pair up Cell splits leaving only one of each pair Cells split again to leave gametes

Question 29

What is the difference between mitosis and meiosis?

Answer 29

Mitosis produces two identical cells with 46 chromosomes, no pairing occurs, asexual Meiosis produces four different cells with 23 chromosomes, paring occurs, sexual

Question 30

What is differentiation?

Answer 30

The process by which a cell changes to become specialised

Question 31

What are stem cells?

Answer 31

Undifferentiated cell - embryonic stem cells can turn into any type, adult aren't as versatile

Question 32

What are the advantages of stem cell research?

Answer 32

1) Cure people + save lives 2) Permanent solution 3) Grow new organs for transplants 4) Improves quality of life 5) Discarded embryo destroyed anyway

Question 33

What are the disadvantages of stem cell research?

Answer 33

1) Embryos = people = murder 2) Possible risk of cancer 3) Religious beliefs 4) Long term effects 5) Designer babies??

Question 34

Why did people not accept Mendel's work straight away?

Answer 34

He had no proof - chromosomes could not be seen

Question 35

What was Gregor Mendel's experiment?

Answer 35

Breeding pea plants First cross - all one characteristic Second cross - different characteristics

Question 36

What did Mendel prove?

Answer 36

Characteristics are determined by hereditary units (genes) which could be dominant or recessive

Question 37

What is the difference between a dominant and recessive gene?

Answer 37

Dominant- only need one copy of allele | Recessive - need 2 copies

Question 38

What is the difference between genotype and phenotype?

Answer 38

Genotype - combination of alleles | Phenotype - outward appearance

Question 39

What is the difference between homozygous and heterozygous?

Answer 39

Homo- same genotype | Hetro- different genotype

Question 40

How do you find dominance or recession in family trees?

Answer 40

Find same parents with different child Parents must be heterozygous If parents suffer - dominant If not suffer - recessive

Question 41

What is cystic fibrosis?

Answer 41

Genetic disease- recessive allele Can have carriers Parents must be sufferers or carriers to have affected children

Question 42

What is polydactyly?

Answer 42

Extra fingers/ toes - dominant No carriers Can be inherited if just one parent has it

Question 43

What are the advantages of embryo screening?

Answer 43

1) Help stop suffering 2) Laws stop it going too far 3) Embryos destroyed anyway 4) Treating disorders expensive

Question 44

What are the disadvantages of embryo screening?

Answer 44

1) Pick desirable babies 2) Embryos destroyed 3) Prejudice- genetic problem people bad 4) Expensive

Question 45

How did life begin?

Answer 45

No one knows - primordial soup, comet etc | Lack of reliable evidence since early organisms soft bodied or fossils destroyed

Question 46

What are fossils?

Answer 46

The remains of plants and animals

Question 47

What are the three ways fossils are made?

Answer 47

1) Gradual replacement by minerals where slow decay happens - forms rock-like substance 2) Casts and impressions - when clay hardens around organism 3) Preservation - e.g. Amber + tar pits - no oxygen or moisture, glaciers, peat bogs too acidic

Question 48

What is extinction?

Answer 48

When a species no longer exists because it could not adapt to its surroundings

Question 49

What can cause extinction?

Answer 49

Environmental changes New predator or disease Can't compete for food Catastrophic event

Question 50

What is a species?

Answer 50

Animals that can breed to produce fertile offspring

Question 51

What is speciation?

Answer 51

The development of a new species

Question 52

How does speciation occur?

Answer 52

1) Physical barrier - geographical isolation 2) Slightly different conditions 3) Variation within a species 4) Different characteristics increase chance of survival 5) Better adapted animals pass on favourable genes 6) Variation becomes common 7) Eventually two groups can't produce fertile offspring