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PAPER 2 GCSE Flashcards

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
How are alveoli adapted for gas exchange by diffusion
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
26
How can smoking cause coronary heart disease
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
27
Experiment to show the effect of exercise on breathing
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
28
Why is diffusion essential for gas exchange in living organism
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
29
How is the leaf adapted for gas exchange
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
30
Oxygen gas exchange in a leaf
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
31
Carbon dioxide gas exchange in a leaf
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
32
Water vapour gas exchange in a leaf
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
33
What is the role of stomata in gas exchange
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
34
When does respiration continue
During the night and day
35
What does net exchange of CO2 and oxygen depend on
Light intensity
36
What are waste products of metabolism
Carbon dioxide and oxygen
37
How do plants lose oxygen and carbon dioxide
By diffusion out of the stomata
38
What are the three main organs of excretion
Lungs, kidneys and skin
39
Excretory products of lungs
CO2
40
Excretory products of kidneys
Urine
41
Excretory products of skin
Sweat
42
What are the two main roles of the kidneys
Production and excretion of urine | Osmoregulation - how the body helps regulate the levels of water in the blood
43
What is ultrafiltration
The glomerulus filters the blood so that only filtrate comes through The filtrate is composed of water of small soluble molecules and ions
44
How does ultrafiltration happen in the Bowman’s capsule
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
Where is water reabsorbed in the nephron
The loop of Henle and the collecting ducts
46
What is selective reabsorption
The reabsorption of glucose from the filtrate back into the blood stream
47
Where does selective reabsorption occur
In the proximal convulsed tubule
48
Why does selective reabsorption occur
So that glucose and other useful molecules are not lost and can be used by the body
49
What is the role of ADH
helps the kidneys reabsorb more water from urine so that it maintains the water content of the blood
50
How does ADH do its role
ADH makes the collecting ducts more permeable to water causing water to be reabsorbed into the blood more
51
What does urine contain
Urine contains urea, water and mineral ions
52
Genome
The entire DNA of an organism - the amount of DNA present in a diploid cell
53
What is a chromosome
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
What is a gene
A length of DNA which is part of a chromosome and that controls a characteristic of an organism
55
What do genes do
Genes code for a production of a specific protein
56
Structure of DNA
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
RNA molecule structure
Single stranded | Contains U instead of T
58
Transcription in protein synthesis
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
Translation in protein synthesis
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
What is mRNA
Messenger RNA - this is created when a gene is transcribed
61
What are ribosomes
Ribosomes are organelles that are the site of protein production
62
What is tRNA
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
What is a codon
A sequence of three bases on a messenger RNA molecule that codes for a specific amino acid
64
What is an anticodon
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
What is an allele
Alleles are different forms of a gene which give rise to differences in inherited characteristics
66
Dominant meaning
This is an allele that will be expressed in the phenotype
67
Recessive meaning
This allele will not be expressed in the phenotype if there is a dominant allele of that gene present
68
Homozygous meaning
A genotype with both alleles being the same
69
Heterozygous meaning
A genotype with both alleles being different
70
Phenotype meaning
How the gene is expressed in the organism (appearance)
71
Genotype meaning
This is the alleles that an organism has for a certain characteristic
72
Codominance meaning
A pattern of inheritance where neither allele is dominant over the other so both alleles are expressed in the phenotype of the organism
73
What does polygenic mean
A characteristic that is caused by more than one gene (most features are a result of polygenic inheritance rather than single genes
74
Chromosomes in a female
XX
75
Chromosomes in a male
XY
76
Division of a diploid cell by mitosis produces
Two cells that contain identical sets of chromosomes
77
Mitosis occurs during
Growth, repair, cloning and asexual reproduction
78
Division of a cell by meiosis produces
Four cells, each with half the number of chromosomes, and that this results in the formation of genetically different haploid gametes
79
Random fertilisation produces
Genetic variation of offspring
80
Diploid number of chromosomes
46
81
Haploid number of chromosomes
23
82
Variation with a species can be
Genetic, environmental or a combination of both
83
How can change in DNA affect the phenotype
By altering the sequence of amino acids in a protein
84
Mutation is
A rare and random change in genetic material that can be inherited
85
Most genetic mutations have no effect on
The phenotype, some have a small effect and rarely do they have a significant effect
86
Incidence of mutation can be increased by
Exposure to ionising radiation (gamma rays, x rays and UV rays) and some chemical mutagens (chemicals in tobacco)
87
Resistance to antibiotics can increase in
Bacterial populations and appreciate how such an increase can lead to infections being difficult to control
88
Darwin’s theory of evolution by natural selection
- 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
Carbon cycle
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
What do organisms and plants use nitrogen for
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
nitrogen fixing bacteria
converts nitrogen in air into soluble ions (nitrates)
92
an increase in greenhouses gases leads to
enhanced greenhouse effect and leads to global warming
93
nitrifying bacteria in soil
converts ammonium ions into nitrates
94
Denitrifying bacteria in the soil
break down nitrates and return nitrogen gas to the air
95
decomposers in nitrogen cycle
break down urea, egested material (eg faeces) and dead bodies. This results in nitrogen being returned to the soil as ammonium ions
96
greenhouse gases
water vapour, co2, nitrous oxides, methane and CFCs
97
Combustion of Fossil fuels produces Sulfur Dioxide which
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
Incomplete combustion of Fossil fuels produces Carbon Monoxide, which
binds irreversibly to Haemoglobin to reduce capacity of Red blood cells to transport Oxygen
99
consequences of eutrophication
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
effect of deforestation
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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