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GCSE Biology > B2b > Flashcards

B2b Flashcards

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1
Q

What are enzymes?

A

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

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2
Q

What are enzymes made from?

A

Proteins from amino acids in a unique shape

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3
Q

Why do enzymes need the right conditions?

A

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

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4
Q

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

A

37 degrees

pH7

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5
Q

Why do nutrients need to be digested?

A

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

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6
Q

What does amylase do and where is it found?

A

Starch into glucose/ maltose

Mouth, salivary gland, pancreas, small intestine

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7
Q

What does lipase do and where is it found?

A

Lipids into glycerol + fatty acids

Pancreas, small intestine

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8
Q

What does protease do and where is it found?

A

Proteins into amino acids

Stomach (pepsin), pancreas, small intestine

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9
Q

What does the liver do?

A

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

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10
Q

What do the small and big intestines absorb?

A

Small - food

Big - water

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11
Q

How do biological detergents work?

A

Proteases + lipases remove stains like food

They work at lower temperatures

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12
Q

How are enzymes used in food?

A

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

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13
Q

What are the advantages of using enzymes in industry?

A

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

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14
Q

What are the disadvantages of using enzymes in industry?

A

Develop allergies
Conditions must be controlled
Expensive
Contaminations

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15
Q

What is respiration?

A

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

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16
Q

What is the equation for aerobic respiration?

A

Glucose + oxygen into carbon dioxide + water + energy

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17
Q

What is energy used for in plants and animals?

A

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

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18
Q

What happens during exercise?

A

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

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19
Q

What is anaerobic respiration?

A

The incomplete breakdown of glucose

Glucose into lactic acid + energy

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20
Q

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

A

Lactic acid build up is painful + muscle fatigue

Doesn’t release as much energy

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21
Q

What is oxygen debt?

A

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

22
Q

What is DNA?

A

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

23
Q

What is a gene?

A

A short section of DNA

24
Q

How do genes make proteins?

A

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

25
Q

What is an allele?

A

A different version of the same gene

26
Q

What can DNA fingerprinting be used for?

A

Forensic science

Paternity tests

27
Q

Describe the process of mitosis

A

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

28
Q

Describe the process of meiosis

A

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

29
Q

What is the difference between mitosis and meiosis?

A

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

30
Q

What is differentiation?

A

The process by which a cell changes to become specialised

31
Q

What are stem cells?

A

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

32
Q

What are the advantages of stem cell research?

A

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

33
Q

What are the disadvantages of stem cell research?

A

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

34
Q

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

A

He had no proof - chromosomes could not be seen

35
Q

What was Gregor Mendel’s experiment?

A

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

36
Q

What did Mendel prove?

A

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

37
Q

What is the difference between a dominant and recessive gene?

A

Dominant- only need one copy of allele

Recessive - need 2 copies

38
Q

What is the difference between genotype and phenotype?

A

Genotype - combination of alleles

Phenotype - outward appearance

39
Q

What is the difference between homozygous and heterozygous?

A

Homo- same genotype

Hetro- different genotype

40
Q

How do you find dominance or recession in family trees?

A

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

41
Q

What is cystic fibrosis?

A

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

42
Q

What is polydactyly?

A

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

43
Q

What are the advantages of embryo screening?

A

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

44
Q

What are the disadvantages of embryo screening?

A

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

45
Q

How did life begin?

A

No one knows - primordial soup, comet etc

Lack of reliable evidence since early organisms soft bodied or fossils destroyed

46
Q

What are fossils?

A

The remains of plants and animals

47
Q

What are the three ways fossils are made?

A

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

48
Q

What is extinction?

A

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

49
Q

What can cause extinction?

A

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

50
Q

What is a species?

A

Animals that can breed to produce fertile offspring

51
Q

What is speciation?

A

The development of a new species

52
Q

How does speciation occur?

A

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

GCSE Biology (2 decks)

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