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Biology > PAPER 2 GCSE > Flashcards

PAPER 2 GCSE Flashcards

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1
Q

What is present in carbohydrates

A

Carbon, hydrogen, oxygen

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2
Q

What is present in lipids

A

Carbon, hydrogen, oxygen (higher ratio of hydrogen to oxygen in lipids than in carbohydrates)

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3
Q

What is present in protein

A

Carbon, hydrogen, oxygen, nitrogen

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4
Q

Structure of carbohydrates

A

Large molecules made up of smaller basic units (starch and glycogen from simple sugars)

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5
Q

Structure of lipids

A

Large molecules made up of smaller basic units (from fatty acids and glycerol)

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6
Q

Structure of proteins

A

Large molecules made up of smaller basic units (from amino acids)

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7
Q

Testing for starch

A

Drop iodine onto a sample

Brown to blue - black

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8
Q

Testing for glucose

A

Drop benedicts solution into test tube with sample and heat

Blue to orange/red

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9
Q

Testing for protein

A

Drop biurets solution onto a sample

Blue - purple

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10
Q

Testing for lipids

A

Add ethanol into test tube with water and sample, shake well
Colourless - cloudy

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11
Q

What do enzymes do

A

Biological catalysts - lower activation energy for metabolic reactions to speed up the rate of metabolic reactions

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12
Q

Optimum temperature for enzymes

A

As temperature increases the enzyme and substrate move quicker and there are more successful collisions between them
This happens until the optimum temperature for the enzyme is reached where the reactions occur at the fastest rate

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13
Q

Denaturing enzymes

A

After the optimum temperature the enzymes begin to denature and change shape
This means that the active site no longer has a complementary shape to the substrate and the reactions can no longer occur

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14
Q

How does pH affect the functioning of enzymes

A

Each enzyme works within a narrow range of pH
If the pH goes beyond either side of the optimum pH then the enzyme will change shape and denature
The optimum pH is the pH that the enzyme works the fastest at

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15
Q

What is the trachea

A

Tube lined with cartilage
Goes from mouth to the lungs where it splits
Cartilage prevents the trachea from collapsing

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16
Q

What are the ribs

A

Bones that protect the lungs from damage - the ribcage can expand or contract with breathing

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17
Q

What are the bronchi

A

The two tubes that the trachea split into

They have cartilage rings to prevent them from collapsing

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18
Q

What are the bronchioles

A

The small tubes that come from the bronchi that have alveoli on the end

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19
Q

What are alveoli

A

Small air sacs at the end of the bronchioles

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20
Q

What are the pleural membranes

A

Very slippery to help reduce the friction of the lungs rubbing along the inside of the ribcage

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21
Q

Action of intercostal muscles when humans inhale

A

External intercostal muscles contract and make the ribcage life upwards and outwards

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22
Q

Actions of intercostal muscles when human exhale

A

External intercostal muscles relax

Internal intercostal muscles that be contracted consciously to expel air faster

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23
Q

Action of diaphragm when inhaling

A

Diaphragm contracts
It flattens out and moves downwards
That increase the volume of the thorax (chest cavity)
The air pressure decreases inside the thorax
The air pressure outside the lungs is higher and moves into the lungs

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24
Q

Action of diaphragm when exhaling

A

Diaphragm relaxes
Forms a dome shape and moves upwards
This decreases the volume of the chest cavity (thorax)
Air pressure increases inside the thorax
Air pressure inside the lungs is higher and so moves out of the lungs

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25
Q

How are alveoli adapted for gas exchange by diffusion

A

Alveoli are small and have a large surface area to volume ratio
Walls of alveoli are one cell thick to allow for faster diffusion
Capillaries are very close to the alveoli to allow a short diffusion pathway
Inside of alveoli is lined with a surfactant that stops the alveoli from collapsing and also allows oxygen and CO2 to diffuse through

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26
Q

How can smoking cause coronary heart disease

A

Nicotine causes the blood pressure to increase
This can damage the lining of the arteries
The damaged arteries can start to have fatty deposits build up in the damaged areas
These can block the arteries leading to the heart causing less oxygen to reach the heart cells so they cannot respire and die

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27
Q

Experiment to show the effect of exercise on breathing

A

Measure the number of breaths per minute at rest
Exercise for a set amount of time
Measure the breathing rate directly after the exercise
Measure breathing rate every minute after exercise until it reaches back to normal breathing rate

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28
Q

Why is diffusion essential for gas exchange in living organism

A

Diffusion allows oxygen to move into the cells so that aerobic respiration can occur
Diffusion allows carbon dioxide to move out of the cells so that is does not build up and become toxic

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29
Q

How is the leaf adapted for gas exchange

A

The stomata allows gas exchange to occur
The spongy mesophyll has air spaces that allow gases to exchange
The leaf is thin so that it has a short diffusion pathway for oxygen, CO2 and water vapour to diffuse in and out of the leaf

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30
Q

Oxygen gas exchange in a leaf

A

During photosynthesis oxygen is produced to excess. There is a higher concentration of oxygen in the leaf than outside and so oxygen diffuses out through the stomata

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31
Q

Carbon dioxide gas exchange in a leaf

A

Carbon dioxide is used up during photosynthesis, therefore there is a lower concentration of carbon dioxide inside the leaf compared to the outside so carbon dioxide diffuses in through the stomata

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32
Q

Water vapour gas exchange in a leaf

A

Water evaporate inside the leaf. This means there is more water vapour inside the leaf than outside of it so water vapour diffuses out through the stomata

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33
Q

What is the role of stomata in gas exchange

A

Stomata open during the day when the plant is photosynthesising, this allows gas exchange to occur (CO2 to go in and oxygen to go out)
If the plant is dehydrated the stomata close to prevent further water loss

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34
Q

When does respiration continue

A

During the night and day

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35
Q

What does net exchange of CO2 and oxygen depend on

A

Light intensity

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36
Q

What are waste products of metabolism

A

Carbon dioxide and oxygen

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37
Q

How do plants lose oxygen and carbon dioxide

A

By diffusion out of the stomata

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38
Q

What are the three main organs of excretion

A

Lungs, kidneys and skin

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39
Q

Excretory products of lungs

A

CO2

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40
Q

Excretory products of kidneys

A

Urine

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41
Q

Excretory products of skin

A

Sweat

42
Q

What are the two main roles of the kidneys

A

Production and excretion of urine

Osmoregulation - how the body helps regulate the levels of water in the blood

43
Q

What is ultrafiltration

A

The glomerulus filters the blood so that only filtrate comes through
The filtrate is composed of water of small soluble molecules and ions

44
Q

How does ultrafiltration happen in the Bowman’s capsule

A

Due to higher blood pressure in the glomerulus filtrate is pushed into the Bowmans capsule
Larger molecules like proteins as well as red blood cells are too large to fit through into the Bowman’s capsule and so stays in the blood

45
Q

Where is water reabsorbed in the nephron

A

The loop of Henle and the collecting ducts

46
Q

What is selective reabsorption

A

The reabsorption of glucose from the filtrate back into the blood stream

47
Q

Where does selective reabsorption occur

A

In the proximal convulsed tubule

48
Q

Why does selective reabsorption occur

A

So that glucose and other useful molecules are not lost and can be used by the body

49
Q

What is the role of ADH

A

helps the kidneys reabsorb more water from urine so that it maintains the water content of the blood

50
Q

How does ADH do its role

A

ADH makes the collecting ducts more permeable to water causing water to be reabsorbed into the blood more

51
Q

What does urine contain

A

Urine contains urea, water and mineral ions

52
Q

Genome

A

The entire DNA of an organism - the amount of DNA present in a diploid cell

53
Q

What is a chromosome

A

A thread like structure found in the nucleus of a eukaryotic cell - made of DNA and protein and contains the genetic info or genes of an organismn

54
Q

What is a gene

A

A length of DNA which is part of a chromosome and that controls a characteristic of an organism

55
Q

What do genes do

A

Genes code for a production of a specific protein

56
Q

Structure of DNA

A

Two strands coiled to form a double helix

The strands being linked by a series of paired bases (A with T , and C with G)

57
Q

RNA molecule structure

A

Single stranded

Contains U instead of T

58
Q

Transcription in protein synthesis

A

A gene is ‘read’ and a mRNA molecule is created
The mRNA molecule is a copy of the sequence of bases found on gene
mRNA then moves out of the nucleus into the cytoplasm

59
Q

Translation in protein synthesis

A

A ribosome attaches to the mRNA molecule
As the ribosome moves along the mRNA molecule, tRNA molecules carrying amino acids enter the ribosomes
The tRNA molecules that have a complementary anticodon to the codon on the mRNA will have a specific amino acid attached
The amino acids from the tRNA molecules will join together to form a sequence that will be a protein

60
Q

What is mRNA

A

Messenger RNA - this is created when a gene is transcribed

61
Q

What are ribosomes

A

Ribosomes are organelles that are the site of protein production

62
Q

What is tRNA

A

Transfer RNA - these are the molecules that carry amino acids to the ribosome so that the mRNA can be read and the corresponding amino acids can be joined together to make a protein

63
Q

What is a codon

A

A sequence of three bases on a messenger RNA molecule that codes for a specific amino acid

64
Q

What is an anticodon

A

An anticodon is a sequence of three bases found on a transfer RNA molecule which are complimentary to the bases on the codon found on the messenger RNA

65
Q

What is an allele

A

Alleles are different forms of a gene which give rise to differences in inherited characteristics

66
Q

Dominant meaning

A

This is an allele that will be expressed in the phenotype

67
Q

Recessive meaning

A

This allele will not be expressed in the phenotype if there is a dominant allele of that gene present

68
Q

Homozygous meaning

A

A genotype with both alleles being the same

69
Q

Heterozygous meaning

A

A genotype with both alleles being different

70
Q

Phenotype meaning

A

How the gene is expressed in the organism (appearance)

71
Q

Genotype meaning

A

This is the alleles that an organism has for a certain characteristic

72
Q

Codominance meaning

A

A pattern of inheritance where neither allele is dominant over the other so both alleles are expressed in the phenotype of the organism

73
Q

What does polygenic mean

A

A characteristic that is caused by more than one gene (most features are a result of polygenic inheritance rather than single genes

74
Q

Chromosomes in a female

A

XX

75
Q

Chromosomes in a male

A

XY

76
Q

Division of a diploid cell by mitosis produces

A

Two cells that contain identical sets of chromosomes

77
Q

Mitosis occurs during

A

Growth, repair, cloning and asexual reproduction

78
Q

Division of a cell by meiosis produces

A

Four cells, each with half the number of chromosomes, and that this results in the formation of genetically different haploid gametes

79
Q

Random fertilisation produces

A

Genetic variation of offspring

80
Q

Diploid number of chromosomes

A

46

81
Q

Haploid number of chromosomes

A

23

82
Q

Variation with a species can be

A

Genetic, environmental or a combination of both

83
Q

How can change in DNA affect the phenotype

A

By altering the sequence of amino acids in a protein

84
Q

Mutation is

A

A rare and random change in genetic material that can be inherited

85
Q

Most genetic mutations have no effect on

A

The phenotype, some have a small effect and rarely do they have a significant effect

86
Q

Incidence of mutation can be increased by

A

Exposure to ionising radiation (gamma rays, x rays and UV rays) and some chemical mutagens (chemicals in tobacco)

87
Q

Resistance to antibiotics can increase in

A

Bacterial populations and appreciate how such an increase can lead to infections being difficult to control

88
Q

Darwin’s theory of evolution by natural selection

A
  • there is a variation within a species
  • the variation is caused by mutations
  • changing conditions in an environment favours one particular form of the species (which have a selective advantage)
  • more of the individuals with the selective advantage survive and the rest die
  • the mutations that has given the selective advantage to the individuals is more likely to be passed on as offspring (as more individuals with the advantage survive long enough to reproduce)
89
Q

Carbon cycle

A

Carbon is put in the atmosphere in carbon dioxide by

  • respiration (animals, plants)
  • decomposers break down dead material from plants and other organisms and release carbon dioxide into the atmosphere
  • combustion of fuels like fossil fuels or wood

Some carbon is stored in the ground which will eventually turn into fossils

The only way carbon is taken from the atmosphere is by photosynthesis by green plants / algae / cyanobacteria

90
Q

What do organisms and plants use nitrogen for

A

absorb nitrates from soil to make amino acids / protein / nucleotide bases / DNA
When an animal eats a plant, nitrogen from the plant’s proteins becomes proteins in the animal. Nitrogen is also passed from one animal to another by feeding.

91
Q

nitrogen fixing bacteria

A

converts nitrogen in air into soluble ions (nitrates)

92
Q

an increase in greenhouses gases leads to

A

enhanced greenhouse effect and leads to global warming

93
Q

nitrifying bacteria in soil

A

converts ammonium ions into nitrates

94
Q

Denitrifying bacteria in the soil

A

break down nitrates and return nitrogen gas to the air

95
Q

decomposers in nitrogen cycle

A

break down urea, egested material (eg faeces) and dead bodies. This results in nitrogen being returned to the soil as ammonium ions

96
Q

greenhouse gases

A

water vapour, co2, nitrous oxides, methane and CFCs

97
Q

Combustion of Fossil fuels produces Sulfur Dioxide which

A

will dissolve in clouds (Acid rain)
death of Plants and Trees
death of aquatic organisms
Acid rain corrodes Metals (steel) and Limestone in buildings

98
Q

Incomplete combustion of Fossil fuels produces Carbon Monoxide, which

A

binds irreversibly to Haemoglobin to reduce capacity of Red blood cells to transport Oxygen

99
Q

consequences of eutrophication

A

leached minerals from fertiliser
Eutrophication encourages the growth of algae. These prevent sunlight reaching other water plants. These plants die because they are unable to carry out photosynthesis.

100
Q

effect of deforestation

A

leaching - “washing out” from soils any soluble chemicals
soil erosion
disturbance of evapotranspiration and carbon cycle
balance of atmospheric gases

Biology (17 decks)

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