Biology Paper 2 Topics Flashcards
1
Q
What is homeostasis?
A
Homeostasis is the regulation of the conditions inside your body and cells in order to maintain a stable internal environment
2
Q
What is the role of receptors in the body?
A
Receptors detect stimuli ( a change in the environment)
3
Q
What is the role of coordination centres in the body?
A
Coordination centres are responsible for receiving information and coordinating a response
4
Q
What is the role of effectors in the body?
A
Effectors bring about a change
5
Q
What three things does the control systems control?
A
The control systems control body temperatures, blood glucose levels and water content
6
Q
What are neurones?
A
Neurones are cells that carry information as electrical impulses
7
Q
What is the order by which the nervous system undergoes to bring about homeostasis?
A
Stimulus > Receptor > Sensory Neurone > CNS > Motor Neurone > Effector > Response
8
Q
What does the CNS consist of?
A
The CNS consists of the brain and spinal cord
9
Q
How are the parts of the CNS connected?
A
The CNS is connected by neurones
10
Q
What are the two main types of effectors?
A
The two main types of effectors include:
- Muscles = Contracts
- Glands = Secretes hormones
11
Q
What does homeostasis maintain?
A
Homeostasis maintains optimal conditions for enzyme action
12
Q
What is phototropism?
A
Phototropism is when shoots of plants grows towards the light
13
Q
What is auxin?
A
Auxin is a plant hormone which is used to stimulate growth in plants
14
Q
Describe the response of a shoot to sunlight
A
Phototropism
- Shoot is exposed to sunlight
- Auxin accumulates on shaded side
- Cells grow faster on the shaded side
- Shoot bends towards the light
15
Q
What is gravitropism/geotropism?
A
Gravitropism/Geotropism is when roots of plants grow towards gravity
16
Q
Describe the root of the plant during geotropism
A
Geotropism:
- Auxin accumulates on lower side of root
- Auxin inhibits growth on lower side
- Root bends downwards
17
Q
What are the commercial uses of auxin?
A
The commercial uses of auxin include:
- Added to rooting powders to stimulate growth for plant cuttings
- Kills weeds whilst leaving other crops untouched
- Stimulates cell division in tissue culture, promoting cloning of plants
18
Q
What are the commercial uses of giberellin?
A
The commercial uses of gibberellin include:
- Promotes seed germination at any time of the year
- Flowering where no specific conditions are needed
- Makes fruits grow larger
19
Q
What are the commercial uses of ethene?
A
The commercial uses of ethene include:
- Speeds up fruit ripening
- Effects can be blocked to delay ripening in storage
- Controls cell division
20
Q
Which receptors detect the change in the body’s core temperature?
A
Temperature receptors detect the change in the body’s temperature
21
Q
How does the body respond when the body’s temperature is too high?
A
When the body’s temperature is too high, blood vessels dilate and blood flows closer to the skin. Sweat glands also produce sweat to transfer out energy
22
Q
What is Vasodilation?
A
Vasodilation is when the blood vessels dilate and blood flows closer to the skin in order to transfer heat into the environment
23
Q
How does the body respond when the body’s temperature is too low?
A
When the body’s temperature is too low, the blood vessels constrict so less blood flows close to the skin, there is no sweat produced, and the body shivers due to the skeletal muscles contracting
24
Q
What is Vasoconstriction?
A
Vasoconstriction is when the blood vessels constrict so less blood flows close to the skin
25
What is the endocrine system?
The endocrine system is a system made up of glands that secret hormones
26
What is the role of the pituitary gland?
The pituitary gland, also known as the master gland, stimulates other glands
27
Which hormone does the thyroid produce?
Thyroid produces thyroxine
28
Which gland does adrenaline come from?
Adrenaline comes from the adrenal gland
29
Which gland does insulin come from?
Insulin comes from the pancreas
30
Which hormone do ovaries produce?
Ovaries produce oestrogen
31
Which hormone do the testes produce?
Testes produce testosterone
32
What comparisons can be made between hormones and nerves?
Hormones are slower than nerves but hormones last longer
33
How many parents are involved in asexual reproduction?
Asexual reproduction involves one parent
34
Which cell division is involved in asexual reproduction?
Cells in asexual reproduction divide by mitosis
35
What offspring are produced in asexual reproduction?
Genetically identical offspring is produced in asexual reproduction
36
What are the advantages of asexual reproduction?
The advantages of asexual reproduction include;
- Faster than sexual reproduction = means many identical offspring can be produced in favourable conditions
- Only one parent is needed = no energy is wasted finding a mate
37
How many parents are involved in sexual reproduction?
Two parents are involved in sexual reproduction
38
How do the cells divide in sexual reproduction?
The cells divide by meiosis and mitosis in sexual reproduction
39
What are the advantages of sexual reproduction?
The advantages of sexual reproduction include:
- Variation increases the chance of individuals surviving a change in the environment
- Selective breeding can be used to increase variation and increase food production
40
How are gametes formed?
Gametes are formed by meiosis in the reproductive organs
41
What happens at the end of fertilisation?
At the end of fertilisation, after gametes have fused, the normal number of chromosomes is restored. The fertilised cell will then continue to divide by mitosis to form an embryo.
42
What is the process of meiosis?
The process of meiosis:
1) . The cell duplicates its genetic information
2) . The cell divides and each new cell has one copy of each chromosome
3) . Both cells divide again to make four gametes
4) . Each gamete has a single set of chromosomes
43
How many chromosomes do cells contain in meiosis?
In meiosis, the cells contain half the normal number of chromosomes, 23.
44
What is a population?
A Population is all the organisms of one species living in a habitat
45
What is a community?
A community is the populations of different species living in a habitat
46
What is a stable community?
A stable community is a community in which all species and environmental factors are in balance
47
What is an ecosystem?
An ecosystem is the interaction of a community of organisms and the parts of their environment that are non-living
48
What is an adaptation?
An adaptation is a feature that enables an organism to survive in the conditions of its normal habitat
49
What is interdependence?
Interdependence is each species in a community depending upon other species for things eg pollination and seed dispersal
50
Name examples of biotic factors
Examples of biotic factors include new predators, food availability, competition and new pathogens
51
Name examples of abiotic factors
Examples of abiotic factors include wind intensity and direction, CO2 levels (for plants), soil pH and mineral content, temperature
52
What do plants compete for in an ecosystem?
Plants compete for light, space, minerals and water
53
What do animals compete for in an ecosystem?
Animals compete for food, mates and territory in an ecosystem
54
What are the three types of adaptation?
The three types of adaptation include structural, behavioural and functional
55
What is an example of a structural adaptation?
An example of a structural adaptation is white fur in arctic areas, allowing for camouflage
56
What is an example of a behavioural adaptation?
An example of a behavioural adaptation is migration, eg moving away from harsh cold conditions into warmer areas
57
What is an example of a functional adaptation?
An example of a functional adaptation is bears slowing their metabolism during hibernation so they require less energy
58
What are extremophiles?
Extremophiles are organisms adapted to live in extreme conditions
59
What is the order of the food chain?
Consumer > Primary consumer > Secondary consumer > Tertiary consumer > Apex predator
60
What is biomass?
Biomass is the mass of living material
61
How does energy move across a food chain?
Energy thats stored in biomass is transferred along food chains and used by other organisms to build biomass. However, not all energy is transferred as lots are lots through heat, sound etc
62
Why are predator-prey cycles always out of phase with each other?
Predator-prey cycles are always out of phase with each other as it takes a while for one population to respond to changes in another population
63
What are three examples of environmental changes that can affect the distribution of organisms?
Three examples of environmental changes that can affect the distribution of organisms include water availability, temperature, atmospheric gases
64
What can environmental changes that affect organism distribution be caused by?
Changes can be caused by seasonal factors, geographical factors and human interaction
65
Why are organisms with the most suitable characteristics more likely to survive?
Organisms with more suitable characteristics are more likely to survive a change in the environment, as they can adapt and breed so that the offsprings also have the beneficial characteristics
66
How do limited resources affect an ecosystem?
Limited resources in an ecosystem results in more competition
67
What is speciation?
Speciation is the development of a new species by natural selection
68
What does it mean by reaction time?
Reaction time is the time it takes to react to a stimulus
69
Describe a practical that can be used to measure human reaction time
Measuring human reaction time:
- Hold a ruler between the thumb and forefinger of the person being tested
- Drop the ruler without warning and record the distance it falls before it is caught
- Repeat the test several times then calculate the mean distance that the ruler fell
- Repeat the experiment to investigate the effect of a factor on reaction time - eg caffeine or background noise
70
What are the independent, dependent and control variables of the effect of light or gravity on the growth of seedlings practical?
Independant variable = Direction of light
Dependant variable = direction of growth
Control variables = number + type of seeds, water, temperature, light intensity
71
How do you estimate populations of organisms using quadrats?
Estimating populations using quadrats:
1) . Place 1m squared quadrat at random in a field
2) . Count all the daisies within it
3) . Repeat several times and work out the mean number of daisies per quadrant ( total number of organisms divided by the number of quadrats)
4) . Multiply the size of the entire area by the number of organisms per metre squared
72
How do you estimate populations of organisms using transects?
Estimating populations using transects:
1) . Mark out a line using a tape measure
2) . Count the daisies in quadrates placed at regular intervals along the line
3) . Draw a graph to show how the daises are distributed
73
What are the disadvantages of sexual reproduction?
The disadvantages of sexual reproduction is that time and energy is needed to find a mate and its not possible for an isolated individual
74
What are the disadvantages of asexual reproduction?
The disadvantages of asexual reproduction is that there is no variation, offspring are only suited to one habitat and disease may affect all the individuals of a population due to lack of variation
75
What five processes occur during the water cycle?
The processes that occur during water cycle are evaporation, condensation, precipitation, transpiration and percolation
76
Describe what happens during the water cycle
1) . Heat energy from the sun causes the water from oceans and lakes to evaporate. The warm air rises and carries water vapour with it
2) . Water vapour condenses back into liquid to form clouds
3) . Water droplets become too heavy for clouds to hold and precipitates
4) . Water travels through the soil (percolation) and enters back into rivers, lakes and oceans
5) . Plants undergo transpiration where they release water vapour into the air and the cycle continues
77
How is carbon dioxide released in the carbon cycle?
In the carbon cycle, when animals and microorganisms respirate they release carbon dioxide into the atmosphere. This can be done when microorganisms decompose matter and respire. The combustion of fossil fuels that comes from decaying matter also releases carbon dioxide into the atmosphere.
78
How is carbon dioxide taken away from the atmosphere in the carbon cycle?
Carbon dioxide is removed in the carbon cycle when plants photosynthesise
79
What are the different ways our body loses water?
Our body loses water via the lungs when we exhale, through sweat and via kidneys in urine
80
How does blood filter through the kidneys?
Arteries contain the blood which contains urea, water and ions, which are sent through the kidneys. The kidneys convert this into urine which is stored in the bladder. The filtered blood leaves the kidneys via the veins
81
What is selective reabsorption?
Selective reabsorption is when some molecules are absorbed back into the blood
82
What happens to excess amino acids? What is this process called?
Deamination - the process by which excess amino acids are broken down into ammonia. Ammonia is toxic so it is converted into urea to be safely excreted by the kidneys
83
How does the body respond when water levels fall/the concentration of blood becomes to high?
When water levels fall, the pituitary gland releases the hormone ADH. ADH travels to kidneys and causes kidney tubules to become more permeable to water (more water can pass out and be reabsorbed). This means less urine is produced so water levels will increase. ADH production will stop at this point.
84
How does the body respond when the water levels rise/concentration of blood becomes too low?
When water levels rise, no ADH is produced so the kidneys will reabsorb less water and more urine can be produced so water levels will decrease
85
What happens in kidney dialysis?
In kidney dialysis:
Water/urea/ions pass through as blood passes over a semi-permeable membrane (large molecules eg proteins and body cells cannot pass through) > another side of the fluid will contain normal levels of water and ions (no urea) > provides a concentration gradient for urea to diffuse from blood to fluid. Some ions and water also diffuse into fluid > normal levels restored
86
Why is the dialysis fluid regularly refreshed?
The dialysis fluid is regularly refreshed so to maintain a large concentration gradient
87
What is the advantage of kidney dialysis?
The advantage of kidney dialysis is that there is no shortage of dialysis machines
88
What are the disadvantages of kidney dialysis?
The disadvantages of kidney dialysis are that frequent hospital visits are required, patients have to follow a controlled diet, can be expensive long-term
89
What are the advantages of kidney transplants?
The advantages of kidney transplants are that the patients can lead a normal life and that they are only initially expensive
90
What are the disadvantages of kidney transplants?
The disadvantages of kidney transplants are that they can be rejected, so anti-rejection drugs are needed for the rest of their lives and there is a shortage of kidney donors
91
What allele is cystic fibrosis caused by?
Cystic fibrosis is caused by a recessive allele, meaning two lower case letters represent having the disorder, a capital letter with a lower case letter shows that they are a carrier and two upper case letters show that they are unaffected
92
What allele is polydactyly caused by?
Polydactyly is caused by a dominant allele, meaning if on a genetic diagram it is shown as having at least one or two upper case letters, this means they have it. If someone is represented as having two lower case letters, this means they do not have polydactyly
93
What types of genetic embryonic screening are there?
Types of genetic embryonic screening includes:
- Antenatal testing
- Neonatal testing
- Pre-implantation genetic diagnosis (PGD)
- Amniocentesis
94
What is amniocentesis in embryonic screening?
Amniocentesis in embryonic screening is where a needle is inserted into the amniotic fluid that surrounds the foetus and fluid is withdrawn.
Foetal cells in the fluid are then examined for the presence of genetic abnormalities such as Down syndrome and cystic fibrosis.
95
What is gene therapy?
Gene therapy involves inserting copies of a normal allele into the chromosomes of an individual who carries a faulty allele
96
What are the steps for gene therapy?
Steps of gene therapy:
1. identify the gene involved in the genetic disorder
2. restriction enzymes cut out the normal allele
3. many copies of the allele are made
4. copies of the normal working allele are put into the cells of a person who has the genetic disorder due to a mutated or faulty copy of an allele
97
What are chromosomes?
Chromosomes are long threads of DNA, which are made up of many genes
98
What is a gene?
A gene is a small section of DNA in a chromosome
99
What is the genome?
Genome is the entire set of genetic material of an organism
100
What are the benefits of fully understanding the human genome?
The benefits of fully understanding the human genome is being able to treat and understand inherited disorders, searching for genes linked to different types of disease, tracing past human migration patterns
101
What is the peripheral nervous system?
The peripheral nervous system is made up of nerve cells that carry information to or from the CNS
102
What are the adaptations of neurones?
Neurone adaptations:
- Long axons which is insulated by a fatty sheath
- Tiny branches (dendrons) which branch further as dendrites at each end
103
What is a reflex arc?
Reflex arc is an automatic response to a stimulus
104
What happens in a reflex arc?
In a reflex arc, receptor detects stimulus > sensory neurone sends impulse to relay neurone > motor neurone sends impulse to effector > effector produces response
105
Why do muscles work in antagonistic pairs?
Muscles work in antagonistic pairs to ensure a part of the body can move back to its original position after being moved eg biceps and triceps
106
What happens in a synapse?
In a synapse, neurotransmitters diffuse across a gap, stimulates other neurone to transmit an electrical impulse
107
What is the role of ADH?
ADH is released by the pituitary gland and into the kidneys, and it controls water content of blood by increasing reabsorption by the collecting ducts
108
What is the response of the body when it is too hot?
When the body is too hot, sweat is produced which evaporates off the skin and removes heat energy from the skin, blood vessels dilate to allow more blood to flow
109
What is the response of the body when it is too cold?
When the body is too cold, the muscles contract so the body shivers which needs energy from respiration which comes as heat, blood vessels constrict so less blood flows close to the skin and heat is conserved
110
What part of the body monitors body temperature?
The hypothalamus monitors the body temperature
111
How does the body respond when thyroxine levels are too low?
When thyroxine levels are too low, the hypothalamus releases TRH, which causes the pituitary gland to release TSH so thyroid releases more thyroxine
112
How does the body respond when thyroxine levels are normal?
When thyroxine levels are normal, production of TRH and TSH are inhibited
113
How does adrenaline prepare the body for the flight or fight response?
Adrenaline increases breathing rate, increases heart rate, increases the conversion of glycogen into glucose so more energy is released in the muscles, diverts blood away from areas such as digestive system to muscles
114
What happens when there is a high concentration of plasma?
When there is a high concentration of plasma, this means too little water is in the blood, so ADH increases, more water is reabsorbed by nephrones, urine becomes more concentrated
115
What happens when there is a low concentration of plasma?
When there is a low concentration of plasma, this means there is too much water in the blood, so ADH decreases, less water is reabsorbed by nephrons, and the urine becomes more dilute
116
What is the role of testosterone?
Testosterone controls the development of male secondary sexual characteristics
117
What is the role of oestrogen?
Oestrogen controls the development of female secondary sexual characteristics
118
Where are auxins made?
Auxins are made in the tips of shoots and roots (the apical meristems) + can diffuse. This promotes growth through cell division and elongation
119
What happens as a result of a high concentration of auxins?
If there is a high concentration of auxins, cells in stems grow more and cells in rocks grow less
120
How do you find the affect of light intensity on plants?
1) add equal volumes of water to three dishes
2) add seeds and place in warm place
3) allow seeds to germinate
4) one in full light, one in partial light, one in no light
5) measure height once a week
121
What is the process of meisosis?
In meosis:
1) genetic info duplicated, chromsomes pair up
2) 1 st division - chromosomes pairs line up at centre of cell, pairs pulled apart so each new cell only has 1 copy of each chromosome, chromosomes swapped around
3) 2nd division - chromosomes line at centr eagain, arms of chromosomes pulled apart
4) 4 gametes produced
122
What happens during fertilisation?
During fertilisation, gametes fuse and the new cell divides by mitosis. Eventually cells differentiatte as embryo develops
123
What is an allele?
Allele is a version of a gene
124
What is a genotype?
Genotype is combination of alleles you have
125
What is a phenotype?
Phenotype is alleles that determine your characteristics
126
What is cystic fibrosis?
Cystic fibrosis is the buildup of mucus in the air passages. It is caused by a recessive allele.
127
Why does selective breeding reduce variation?
Selective breeding reduces variation because there are less different alleles
128
What is the process of selective breeding?
Animals with desirable characteristics breed together, produce offspring, offspring reproduce with eachother
129
What is genetic engineering?
Genetic engineering is when a gene is isolated using an enzyme, and is inserted into vector eg bacteria
130
What are the pros and cons of GM crops?
Pros - increases yield, less malnourishment in poor areas
| Cons - reduces farmland biodiversity, effects not fully understood
131
How are plants cloned?
Tissue culture (plant cells are put in growth medium with hormones) and cuttings
132
How are animals cloned?
Animals are cloned through embryo transplants
133
What happens in adult cell cloning?
In adult cell cloning, the nucleus of an egg cell is removed and replaced by a nucleus of an adult body cell, it is then stimulated by an electric shock and is implanted into a womb
134
What are the three ways fossils are formed?
Fossils are formed by:
- Gradual replacement by minerals
- -from casts and impressions
- from preservation in places where no decay happens
135
What is speciation?
Speciation is the development of new species, which occurs when populations of same species can no longer breed
136
What happens as a result of overusing antibiotics?
Overusing antibiotics > antibiotic resistant bacteria > made worse by rapid reproduction
137
What is biogas?
Biogas is made by anaerobic decay of waste material
