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Final Biology Edexcel IGCSE - Hard Content > Hard Content > Flashcards

Hard Content Flashcards

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1
Q

Describe the process of transcription:

A
  1. RNA polymerase binds to non coding region of DNA
  2. the two DNA strands unzip and the RNA polymerase moves along one of the strands of DNA
  3. it uses the coding DNA in the gene as a template to make the mRNA. Base pairing ensures mRNA is complementary to gene
  4. once made mRNA moves out of nucleus and into ribosome.
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2
Q

Describe the process of translation

A
  1. amino acids are brought to ribosome by tRNA
  2. the order in which amino acids are brought matches order of codons on mRNA
  3. the anticodons on tRNA are complementary to codon for amino acid ensuring amino acids are brought in correct order
  4. amino acids are joined together by ribosome making protein
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3
Q

Define DNA:

A

a large biomolecule made up of nucleic acids that forms a digital code

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4
Q

What is a gene?

A

a sequence of DNA that codes for a specific protein

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5
Q

What is mitosis?

A

cell division for growth, tissue repair and asexual reproduction

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6
Q

What is meiosis?

A

cell division to create haploid gametes

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7
Q

Define phenotype:

A

the outwards expression of the genotype

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8
Q

Define genotype:

A

the alleles that you have

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9
Q

What is a codon?

A

a triplet code that codes for an amino acid

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10
Q

Define an allele:

A

different versions of genes

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11
Q

Define genetic variation:

A

the differences in the sequence of bases of a gene between species or between individuals of the same species

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12
Q

Meiosis: how many chromosomes in original cell?

A

46

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13
Q

Mitosis: how many chromosomes in original cell?

A

46

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14
Q

Mitosis: How many daughter cells?

A

2

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15
Q

Meiosis: how many daughter cells?

A

4

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16
Q

Mitosis: how many chromosomes in daughter cell?

A

46

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17
Q

Meiosis: how many chromosomes in daughter cell?

A

23

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18
Q

State two features of a virus?

A
  • made of biomolecules
  • viruses make copies of themselves to infect cells and take it over in order to manufacture the cell to make components that make up virus
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19
Q

State five features of plants:

A
  • multi cellular
  • cells contain chloroplast
  • able to photosynthesise
  • cellulose cell walls
  • store carbs as starch or sucrose
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20
Q

State 6 features of animals:

A
  • multi cellular
  • do not contain chloroplasts
  • unable to photosynthesise
  • have no cell wall
  • store carbs as glycogen
  • has nervous coordination
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21
Q

State four features of bacteria:

A
  • single cellular
  • have no cell wall, membrane or cytoplasm
  • no nucleus but circular chromosome of DNA
  • can photosynthesis but must feed off of dead matter
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22
Q

State four features of fungi:

A
  • no photosynthesis
  • organised into mycelium made of hyphae containing nuclei
  • cell walls made of chitin
  • feed by extracellular secretion
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23
Q

What is a a stem cell?

A

an unspecialised cell

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24
Q

If a plant cell is placed in pure water…

A

water moves into cell, turgid

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25
Q

If a plant cell is placed in a hypertonic solution…

A

water moves out of cell, flaccid then plasmolysed

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26
Q

If an animal cell is placed in pure water…

A

water moves into cell, burst/lysis

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27
Q

If an animal cell is placed in hypertonic solution…

A

water moves out of cell, crenated

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28
Q

Large SA:V ratio = ………………….. diffusion

A

faster

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29
Q

Mouth:

A

mechanical digestion

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30
Q

Oesophagus:

A

peristalsis by muscular tube

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31
Q

Salivary gland:

A

produce saliva containing amylase

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32
Q

Stomach:

A

muscular organ where chemical digestion occurs

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33
Q

Pancreas:

A

produces enzymes

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34
Q

Liver:

A

produces bile

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35
Q

Gall bladder:

A

stores bile

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36
Q

Duodenum:

A

where food is mixed with enzymes and bile

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37
Q

Ileum:

A

where digested food is absorbed into blood

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38
Q

Colon:

A

where water is reabsorbed

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39
Q

Rectum:

A

where fences is stored

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40
Q

Anus:

A

where faeces leave the alimentary canal

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41
Q

Maltase location =

A

small intestine

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42
Q

Amylase location:

A

mouth + pancreas

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43
Q

Protease location =

A

stomach + pancreas

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44
Q

Lipase location =

A

pancreas

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45
Q

What is the xylem made from?

A

dead xylem cells

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46
Q

What is special about xylem cells?

A

they don’t have cells walls at the end of the cells forming a continuous stream

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47
Q

What makes the xylem cell wall thick?

A

lignin

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48
Q

What does the phloem consist of?

A

a column of living cells

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49
Q

What are sieve plates?

A

holes in the ends of phloem cells that allow dissolved sugars to be transported

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50
Q

What effect does humidity have on transpiration and why?

A

decrease, concentration gradient is less steep

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51
Q

What effect does temperature have on transpiration and why?

A

increases, evaporation and diffusion occur at faster rate

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52
Q

What effect does wind speed have on transpiration and why?

A

increases, removes water vapour at quicker speed keeping gradient steep

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53
Q

What effect does light intensity have on transpiration and why?

A

increases, stomata open wider in bright light allow more CO2 in

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54
Q

Describe the water pathway:

A
  1. water from soil into root hair cells via osmosis
  2. moves into root cortex cell via osmosis
  3. moves into xylem via osmosis
  4. moves up xylem by transpiration stream
  5. moves into mesophyll cells by osmosis
  6. water evaporates into spaces in spongey mesophyll layer, followed by diffusion through stomata
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55
Q

What does the xylem transport?

A

water and dissolved minerals

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56
Q

What does the phloem transport?

A

sucrose and amino acids

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57
Q

Define the transpiration stream:

A

the removal of water from the leaf, producing a tension from above creating a water potential gradient in the xylem, drawing cohesive water molecules up the plant

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58
Q

Homeostasis:

A

the maintenance of a constant internal environment

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59
Q

Negative feedback:

A

a change in the internal conditions is detected and starts a process that returns the conditions to normal

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60
Q

Correcting action:

A

the opposite to the change

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61
Q

Thermal regulation:

A

the maintenance of a balance between the heat generated and the heat lost by the body

62
Q

What are 4 typed of heat transfers?

A

radiation, evaporation, conduction, convection

63
Q

How does vasodilation work?

A

blood vessels close to surface of skin widen

64
Q

Function of testosterone:

A

stimulate growth of secondary characteristics

65
Q

Function of adrenaline:

A

increase BR and HR

66
Q

Function of insulin:

A

to control blood glucose levels

67
Q

Function of ADH:

A

control of water levels

68
Q

4 steps of ultrafiltration:

A
  1. blood from renal artery flows through glomerulus
  2. a high pressure is built up which squeezes water, urea, ions and glucose out of blood and into Bowman’s capsule
  3. the membranes in-between glomerulus and Bowman’s capsule act like filters
  4. filtered liquid is known as glomerular filtrate
69
Q

Describe the 3 steps of selective re-absorption:

A
  1. all glucose is reabsorbed in proximal convoluted tubule so it can be used in resp
  2. sufficient ions reabsorbed
  3. sufficient water reabsorbed from collecting duct
70
Q

What are three functions of the kidney?

A

removal of urea, adjustment of salt levels, adjustment of water content

71
Q

What are the four steps for testing for starch in plants?

A
  1. leaf in hot water to get rid of waxy cuticle
  2. ethanol/ hot water bath to remove chlorophyll
  3. rinse and cool
  4. lay flat and use iodine
72
Q

What makes up the female part of the flower?

A

stigma and style make up carpel

73
Q

What makes up the male part of the flower?

A

anther and filament make up stamen

74
Q

What are four minerals needed by plants?

A

nitrates, potassium, magnesium and phosphates

75
Q

What is the function of magnesium in plants?

A

needed for photosynthesis

76
Q

What is the function of phosphate in plants?

A

ATP, cell membranes and DNA

77
Q

What is the function of nitrates in plants?

A

growth and enzymes

78
Q

What are four leaf adaptations?

A

stomata control gas exchange, thin leaf shape decreases diffusion distance, spongey mesophyll layer is moist and large SA created by air spaces

79
Q

Define germination:

A

when roots and shoot emerge from soil

80
Q

What is the function of potassium in plants?

A

photosynthesis and enzyme function

81
Q

What are the six steps in fertilisation?

A
  1. pollen tube grows down style
  2. enzymes secreted by tip which digest style tissue
  3. male gamete travels to ovule
  4. male gamete enters ovule through micropyle
  5. fuses with nuclei of female gamete
  6. forms zygote that grows into embryo
82
Q

What is the colour change in hydrogen carbonate indicator?

A

HIGH= yellow NORMAL= orange LOW= purple

83
Q

How do auxins work in positive phototropism?

A

auxin is made in stem tip, diffuses away from light and accumulates in shaded bit of plant, causes cell elongation making tip bend towards light

84
Q

What is a tropism?

A

a plants response to a stimulus by produces hormones that affect plant growth

85
Q

What is geotropism?

A

growth in response to gravity

86
Q

What is phototropism?

A

growth in response to light

87
Q

(animals) anaerobic respiration:

A

glucose -> lactic acid

88
Q

(Plants) anaerobic respiration:

A

glucose -> ethanol + CO2 + water

89
Q

What does plasma contain?

A

salts, glucose, amino acids, urea, proteins, fat, vitamins

90
Q

What is the function of the pleural membranes?

A

lubrication

91
Q

Emphysema:

A

Emphysema is when he alveoli wall become damaged due to smoking and therefore the SA reduces for gas exchange. patient may feel short of breath.

92
Q

Bronchitis/smokers cough:

A

Tar in cigarettes damages the cilia in your lungs and trachea. when these are damaged they cannot sweep away dust and bacteria meaning infections are likely/smokers cough.

93
Q

Nicotine:

A

an addictive stimulant that causes an increased release of dopamine, which can cause loss of appetite and increases heart rate.

94
Q

Describe the primary immune response:

A

When lymphocytes come across a foreign antigen they will start to produce proteins called antibodies which lock onto the invading pathogen and mark them for destruction by the phagocyte. Antibodies specific to that type of antigen are then produced rapidly, including memory cells that can remember the antigen if it were to enter again, meaning antibodies can be produced faster and in greater quantities.

95
Q

Two features of vein:

A

large lumen, has valves

96
Q

Two features of artery:

A

small lumen, thick elastic walls

97
Q

Two features of capillary:

A

very small lumen, one cell thick wall

98
Q

Describe four steps to CHD:

A
  1. clot prevents glucose and oxygen reaching cardiac muscle
  2. muscles will respire anaerobically
  3. large build up of lactic acid
  4. muscle will die an be unable to contract
99
Q

Phagocyte:

A

engulfs and destroys pathogens (lobed nucleus)

100
Q

Lymphocyte:

A

release antibodies to bind to a neutralise pathogens

101
Q

Define neurotransmitter:

A

chemical substance that transfers a message from one neurone to another

102
Q

What are the four steps in reflex arc?

A
  1. stimulus is detected by receptors, an impulse is sent along sensory neurone to CNS
  2. in CNS neurone passes message onto relay neurone
  3. impulse is relayed to motor neurone
  4. muscle contracts
103
Q

Nerve:

A

a group of axons and many neurones

104
Q

Neurone:

A

a single cell of the nervous system

105
Q

Response:

A

a reaction to a stimulus

106
Q

Receptor:

A

organ that detects the stimulus

107
Q

Effector:

A

organ that produces effect to stimulus

108
Q

What are the three types of neurone = :

A

relay, motor, sensory

109
Q

Iris reflex in bright light:

A

pupils get smaller, radial muscles relax, circular muscles contract

110
Q

Iris reflex in dim light:

A

pupil gets bigger, radial muscles contract, circular muscles relax

111
Q

Iris reflex looking at distant objects:

A

ciliary muscles relax, pulling sensory ligaments tight, making lens go thin and refract less light

112
Q

Iris reflex looking at near objects:

A

ciliary muscles contract slackening the suspensory ligaments, making lens go fat and refract light more

113
Q

Conjunctiva:

A

lubricates and protects eye

114
Q

Sclera:

A

tough outer layer that protects eye

115
Q

Cornea:

A

refracts light into the eye

116
Q

Iris:

A

controls diameter of pupil and how much light enters

117
Q

Pupil:

A

hole in eye that lets light in

118
Q

Lens:

A

focuses light onto retina

119
Q

Retina:

A

light sensitive part covered in rods and cones

120
Q

Optic nerve:

A

carries impulse from receptor to brain

121
Q

6 steps in signal travelling across synapse:

A
  1. impulse moves down axon towards axon terminal
  2. vesicles containing NTs moves towards pre SM
  3. NT is released into synapse and diffuses across post SM
  4. NT binds onto receptors on post SM
  5. when enough receptors have NTs a new impulse is generates on post SM
  6. after NT is broken down by enzymes
122
Q

What are the five greenhouse gases?

A

Co2, methane, water vapour, nitrous oxides, CFC

123
Q

What are the 6 stages in antibiotic resistance?

A
  1. a natural population of bacteria that has some susceptible and some resistant
  2. YOU START TAKING THE ANTIBIOTIC
  3. the susceptible bacteria die first
  4. you keep taking the AB, more bacteria die until only the resistant are left
  5. you stop taking the antibiotic, the resistance bacteria reproduce
  6. now you have a resistant population which the AB won’t work against
124
Q

What are the three steps in natural selection?

A
  1. organism with most suitable characteristics for the environment have better chance at survival
  2. they will then have an increased chance at breeding and passing on their genes
  3. greater proportion of next population will have better alleles (the best features are naturally selected)
125
Q

What is the theory of evolution?

A

all species of living things have evolved from simple life forms that first developed more than 3 million years ago

126
Q

In what two ways can genetic variation occur?

A

genetics or environment

127
Q

What are three steps to selective breeding?

A
  1. form existing stock, select ones with best characteristics
  2. breed them
  3. select best offspring and breed them etc
128
Q

How does genetic variation occur by genetics?

A

each human will inherit one allele for each characteristic from their parent, which allele is expressed is determined by dominance

129
Q

Define mutation:

A

random events that change the base sequence of DNA

130
Q

Why is variation important?

A

helps species survive, range of alleles ensures genetic strength

131
Q

What are four steps in micro-propagation?

A
  1. specialised part of plant taken from parent plant
  2. tissue sample is places in agar growth medium containing nutrients and auxins, allowing sterile growth
  3. samples develop into tiny plantlets
  4. platelets are planted into compost
132
Q

What is genetic engineering?

A

changing the genetic material of an organism

133
Q

What are the five steps of genetic engineering?

A
  1. required gene is removed from chromosome with restriction enzyme
  2. plasmic is removed from bacteria and cut open with same restriction enzyme
  3. removed gene is inserted into plasmid using ligase enzyme
  4. plasmid is replaced into bacterium
  5. bacterium is allowed to grow and multiply
134
Q

Two pros of genetic engineering:

A

can produce perfect protein and modified crops have better growth rates

135
Q

Two cons of genetic engineering:

A

possible long term effects on species, cross fertilisation between crops

136
Q

Describe reproductive cloning in sheep:

A

adult diploid cell of Sheep 1 (organism being cloned) is removed. nucleus is removed from diploid cell. mature enucleated egg cell removed from sheep 2. mild electric shock puts diploid nucleus into enucleated egg cell. sheep 3 acts as a surrogate. clone of sheep 1 is born.

137
Q

What are the two types of cloning?

A

reproductive and therapeutic

138
Q

What are four drawbacks of animal cloning?

A

inefficient, organ defects, premature ageing, illegal to clone humans

139
Q

What are the five steps in bread making?

A
  1. yeast + sugar + water + flour + left in warm place
  2. yeast respires aerobically
  3. yeast then ferments until there is no 02 left
  4. CO2 makes dough rise
  5. cooking bread kills yeast, evaporates ethanol and makes bread rise even more
140
Q

What are the five steps in beer/wine production?

A
  1. barley grains placed in warm water so they germinate
  2. enzyme grains break starch into sugary solution (malting)
  3. sugary solution is extracted and yeast is added
  4. yeast ferments
  5. hops added for flavour
141
Q

Define a pest?

A

an organism that lessens the production of a crop

142
Q

5 benefits of a poly tunnel:

A

transparent material allows light, lights can extend day, greenhouse effect, burning FF raises temp and produces Co2 and water, water vapour maintains moist atmosphere

143
Q

Five conditions a farmer can control:

A

temp, Co2 conc, light, soil, pests

144
Q

What are three types of chemical pesticides?

A

herbicides, pesticides, fungicides

145
Q

What is a biological pesticide?

A

the use of another organism to reduce pest numbers

146
Q

Yeast + oxygen ->

A

Co2 + water

147
Q

Yeast ->

A

ethanol + Co2

148
Q

Three cons of synthetic fertiliser:

A

expensive, can affect soil structure, eutrophication

149
Q

Two pros of synthetic fertiliser?

A

easy to store and use, land does not need rest periods in-between growth

150
Q

Define fertiliser:

A

substance that add minerals to soil

151
Q

What are two types of non artificial fertilisers?

A

manure and slurry

Final Biology Edexcel IGCSE - Hard Content (1 decks)

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