Biology Paper 2 Flashcards
(120 cards)
1
Q
What is the role of the human nervous system?
A
The nervous system detects stimuli from the internal or external environment and uses electrical impulses to bring about fast, but short-lived, responses
2
Q
Describe 2 ways of measuring reaction time
A
Dropping a ruler and catching it, computerised tests involving pressing a button in response to seeing something on the screen time recorded by the computer
3
Q
Summarise the order of how the nervous system works.
A
Stimuli, receptor, sensory neurone, CNS, motor neurone, effector, response
4
Q
Name 3 types of neurone
A
Sensory, Motor and Relay
5
Q
What is a synapse and how does it work?
A
The method by which a nervous impulse crosses the gap between neurones.
1. Impulse arrives at the end of neurone A
2. Neurotransmitter is released into the synaptic gap
3. Neurotransmitter diffuses across the synaptic gap
4. Neurotransmitter binds to receptors on neurone B
5. A new electrical impulse is generated in neurone B
6
Q
What neurone is involved in a reflex?
A
Relay
7
Q
Why are reflexes important?
A
Reactions to remove your body from danger
8
Q
Why are reflexes faster?
A
They do not involve the brain, therefore no conscious thought
9
Q
What is a receptor? State 3 examples
A
Cells that detect stimuli (changes in the internal or external environment).
Eyes, ears, skin, thermoreceptors, pressure receptors, tongue, nose
10
Q
What is a stimulus?
A
A change in the environment (internal/external)
11
Q
What carries out a response? Give 3 examples
A
Effectors- Muscle, gland or organ
12
Q
How is a nerve cell adapted?
A
The cell body contains the cytoplasm and nucleus (the control centre of the cell)
The axon is a long extension of the cytoplasm (can be up to 1m). This means nerve impulses can be transmitted to the extremities by one cell
The myelin sheath is a fatty layer that surrounds the axon. The sheath acts as an insulator and speeds up nerve impulses.
The branched ends of the axon and the smaller branches coming from the cell body allow the neurone to make connections with many other neurones
13
Q
What is the endocrine system made of?
A
Gland and hormones
14
Q
How are chemical messages transported around the body?
A
Glands release hormones into bloodstream, which then travel to the target organ to produce an effect
15
Q
What is produced if blood glucose is a) too high or b) too low?
A
a) Insulin
b) Glucagon
16
Q
Name 2 places in the body where glycogen is stored.
A
Muscles and liver
17
Q
What is the process called that restores the body back to normal levels?
A
Negative feedback
18
Q
How is water lost from the body?
A
Urine, respiration, sweating, breathing
19
Q
What is the function of the kidneys?
A
To filter the blood and remove waste materials such as toxins and urea
20
Q
Name the hormones involved in reproduction (male and female)
A
Testosterone
Oestrogen
Follicle stimulating hormone
Luteinising hormone
21
Q
State the names and functions of the hormones in the menstrual cycle
A
FSH - Matures the egg
Oestrogen- Causes uterus lining to thicken and stop FSH production
LH - Releases the mature egg
Progesterone - Maintains uterus lining and stops FSH and LH production
22
Q
What are the 2 main categories of contraception?
A
Physical barriers and chemical methods
23
Q
Summarise the stages of IVF
A
- Mother given FSH and LH to mature several eggs
- Eggs collected and fertilised in a laboratory
- Fertilised eggs develop into embryos
- Some embryos are inserted into the mothers uterus
24
Q
State 2 advantages and 2 disadvantages of fertility
treatment.
A
Disadvantages- emotionally draining, physically stressful, low success rate, multiple births
Advantages- allows pregnancy when not possible, embryo screened for genetic disorders
25
What are gametes?
Sex cells
26
What is the difference between sexual and asexual reproduction?
Sexual reproduction involves 2 parents and produces genetically different offspring, asexual involves one parent and produces genetically identical offspring
27
Give 2 advantages and 2 disadvantages of sexual reproduction
Advantages - variation, increases diversity, species can adapt to new environments, disease is less likely to have an impact
Disadvantages - long time, energy is needed, not possible for an isolated individual
28
Give 2 advantages and 2 disadvantages of asexual reproduction
Advantages - produce large quantities of identical offspring, quic, easy, no variation
Disadvantages - genetic disorders are passed on, no variation
29
What organism uses both sexual and asexual reproduction?
Plants
30
What type of cell division forms gametes?
Meiosis
31
Name the gametes in animals.
Sperm and egg
32
Name the gametes in plants.
Ovule and pollen
33
What does sexual reproduction lead to that asexual does not?
Variation
34
What effect does meiosis have on chromosome number?
Halves it
35
When a new cell is formed by fertilisation, what type of cell division takes place?
Mitosis
36
What is the process by which cells develop into specific types?
Differentiation
37
Where is genetic material found?
Nucleus
38
Describe the structure of DNA.
Double helix
39
What is a gene and what is its function?
A section of DNA that codes for a particular protein
40
What is the Human Genome Project?
Mapping of all the genes in a human
41
State 3 ways in which understanding the Human Genome Project is important.
To search for genes linked to different types of disease
To understand and treat inherited disorders
To trace early human migration patterns
42
Where does protein synthesis happen in a cell?
Ribosome
43
What is a change in the sequence of DNA called?
Mutation
44
What is an allele?
A version of a gene
45
What is the difference between a dominant and recessive allele?
Dominant - The individual only needs one copy of this allele for its phenotype to be seen
Recessive - The individual needs two copies of this allele for its phenotype to be seen
46
What is the difference between heterozygous and homozygous?
Homozygous - The individual has two identical alleles for this gene
Heterozygous - The individual has two different alleles for this gene
47
What is the difference between genotype and phenotype?
Genotype - The genetic makeup of an organism for a particular gene (e.g. RR)
Phenotype - The displayed characteristics due to the interactions between alleles (e.g. red flowers)
48
What are the genotypes for a a) male and b) female?
Male XY, female XX
49
What is variation?
Variation is differences between organisms within the same species or between different species
50
State 3 causes of variation
Environmental, genetic, combination of both
51
What is evolution?
The gradual development/ changing of an organism from an earlier form
52
What is a species?
Organisms that can interbreed to produce fertile offspring
53
What is natural selection?
The process by which evolution takes place - those with favourable characteristics (best suited to environment) more likely to survive and reproduce, passing on their genes
54
What is selective breeding?
The process by which humans breed plants and animals for particular genetic characteristics
55
State 2 advantages and 2 disadvantages of selective breeding.
AD: Desired characteristics can be inherited, increased profit for items that you can increase yield
DIS: Inbreeding - some breeds are prone to disease or inherited defects may not get the characteristics you desire
56
What is genetic engineering?
The process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic
57
What structures present in a prokaryote are used in genetic engineering?
Plasmids
58
What are used to “cut out” and “stick” an inserted section of DNA?
Cut - restriction enzymes
Stick - ligase enzymes
59
State 2 advantages and 2 disadvantages of genetic engineering
AD: Improved growth rates / Increased yield / Increased food quality / Produce human proteins / enzymes as medicine
DIS: Unknown effects on populations of wild flowers / Unknown effects on populations of insects / Some people feel the effects of eating GM crops / Effects on healthy humans have not been fully explored
60
State 2 uses of genetic engineering
Insulin production, disease resistant crops, monoclonal antibodies
61
Who is credited with the theory of natural selection and evolution?
Charles Darwin
62
State the 3 stages of natural selection
1. Individual organisms within a particular species show a wide range of variation for a characteristic
2. Individuals with characteristics most suited to the environment are more likely to survive to breed successfully
3. The characteristics that have enabled these individuals to survive are then passed on to the next generation
63
What is speciation?
The formation of new and distinct species in the course of evolution
64
What are fossils?
The remains of organisms from millions of years ago, found in rocks
65
What is an evolutionary tree?
Can be used to determine how much or how little organisms have changed as life developed on Earth
66
What do the junctions between the lines on an evolutionary tree mean?
Evolutionary trees are used to represent the relationships between organisms
67
What do the junctions between the lines on an evolutionary tree mean?
A common ancestor of two species
68
What is extinction?
When there are no remaining individuals of a species still alive
69
State 3 ways that extinction could occur.
Changes to the environment over geological time; lack of food/prey; new predators; new diseases; new, more successful competitors: single catastrophic event / natural disaster
70
State the title at each classification level
Domain, Kingdom, Phylum, Class Order, Family, Genus, Species
71
Which 2 levels are used in the binomial naming system?
Genus and Species
72
What are the 3 domains?
Archaea, Bacteria, Eukarya
73
What is an ecosystem?
The interaction of a community with the abiotic parts of the environment
74
What do organisms need to survive and reproduce?
Water, food, light, space, oxygen, carbon dioxide, mates
75
State 4 things that a plant competes for
Water, space, light, carbon dioxide, oxygen
76
State 4 things that an animal competes for
Food, sexual mates, hierarchy, territory
77
Describe the differences between biotic and abiotic factors (give an example of each)
Abiotic is a non living factor such as temperature or carbon dioxide.
Biotic is a living factor such as a predator or disease.
78
What is an extremophile? Give an example
(micro)organisms that live in environments that are very extreme (eg. high temp, pressure, salt conc)
79
Write a 4-stage food chain and label the producer, secondary consumer, primary consumer, tertiary consumer, herbivore, carnivore and omnivore.
Example must start with a plant (producer)
Followed by an organism that eats the plant (primary consumer), followed by a secondary consumer then a tertiary consumer.
80
Describe the difference between a predator and its prey.
Predator is an animal that eats prey.
Prey is the animal that gets eaten.
81
What is biodiversity?
A measure of the variety of all the different species of organisms within an ecosystem
82
What does having greater biodiversity ensure stability in an ecosystem?
Each species becomes less dependent on specific species for food/shelter --> less pressure on certain species which could've lead to extinction --> all species populations are balanced
83
State 2 methods to determine the distribution and abundance of species in an ecosystem.
Random sampling using a quadrat
Systematic sampling using a transect
84
What are the differences between random and systematic sampling?
Random sampling can be used to measure the distribution of one organism over a large area, systematic sampling can be used to see how the distribution of organisms change across one or more habitats.
85
Name 3 substances that can be recycled in our atmosphere.
Carbon, nitrogen and water
86
State 3 process that return carbon dioxide to the atmosphere.
Respiration, combustion, decomposition
87
What uses carbon dioxide from the atmosphere?
Plants
88
Where does fresh water for plants and animals come from?
Ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers, streams and underground
89
State 3 factors that affect the rate of decay of biological material.
Availability of oxygen, temperature and moisture levels
90
How do humans affect the amount of land for animals and plants?
Reduce the amount of land by deforestation for farming, agriculture or building
91
What is a peat bog?
Very wet areas of land without trees and where many types of moss grow. They are acidic and often have very low levels of nutrients. Lots of partially decayed organic material.
92
Why are peat bogs being destroyed? What is the impact of this?
To use as fuels or for agriculture. The impact is that when they are destroyed, they no longer take in large amounts of carbon and store it so contribute to the greenhouse effect and increased carbon dioxide levels.
93
As population increases what is happening to a) resources and b) amount of pollution?
a) Resources are decreasing
b) Pollution is increasing
94
How is water, air and land polluted?
Water - litter, fertiliser, chemicals, pesticides
Air - Greenhouse gases, carbon dioxide, sulfur dioxide, particulates
Land - litter, chemicals
95
What is the impact of pollution on biodiversity?
Reduces biodiversity
96
Why is a reduction in biodiversity concerning?
Reduced genetic diversity in organisms, can lead to extinction of species
97
Give 3 causes of deforestation.
1. Provide land for cattle or rice fields
2. Grow crops for biofuels
3. To clear space for building
98
Which 2 gases are increasing in the atmosphere that are contributing to global warming?
1. Carbon dioxide
2. Methane
99
State 3 consequences of global warming.
1. Increased spread of pathogens
2. Affecting migration patterns of animals
3. Melting of polar ice caps, causing flooding
4. Reduced habitats in polar regions
5. Reduced biodiversity
100
State 3 positives and 3 negatives about human interaction in an ecosystem.
POSITIVE
1. Breeding programmes for endangered species
2. Protection and regeneration of rare habitats
3. Reintroduction of field margins and hedgerows in agricultural areas where farmers grow only one type of crop
4. Reduction of deforestation and carbon dioxide emissions by some governments
5. Recycling resources rather than dumping waste in landfill
NEGATIVE
1. Clearing of land for agriculture, buildings and/or transport
2. Hunting of rare species
3. Mining from the land
101
What is a trophic level?
The position a species occupies in a food chain.
102
What type of organisms are found in trophic level 1?
Plants and algae.
103
What group of organisms break down dead, organic material?
Decomposers (microorganisms).
104
What do pyramids of biomass represent?
The relative amount of biomass in each level of a food chain.
105
Approximately how much light is absorbed by plants?
1%-2%
106
State 2 ways in which biomass is lost through a food chain.
1. Not all the ingested material is absorbed.
some is egested as faces
2. Some absorbed material is lost as waste, such as carbon dioxide and water in respiration and water and urea in urine
107
Approximately how much energy is transferred between each trophic level?
10%
108
What is global dimming?
Global dimming is defined as the decrease in the amounts of solar radiation reaching the surface of the Earth
109
What is an antigen?
Proteins on cell surface for cell recognition
110
What is a toxin?
A chemical or antigen that causes illness
111
What drugs must patients who receive a transplant take? Why?
Immunosuppressant drugs to prevent rejection
112
What is phagocytosis?
When a phagocyte is attracted to a pathogen, binds to it, then engulfs it.
Enzymes then break down the pathogen.
113
Describe the role of T Cells.
Some can destroy cells and other stimulate an immune response
114
Describe the roles of B Cells.
Release antibodies
115
What is the purpose of a memory cell?
Remember the same pathogen for faster antibody production in future infections.
116
What are the differences between active and passive immunity?
Active immunity is when the person is exposed to a live pathogen, develops the disease and produces antibodies. Passive immunity is when antibodies are transferred.
117
Why is the secondary response quicker than the primary immune response?
Memory cells already know what antibodies to make to destroy the pathogen. This is done in a much quicker time than when you first encounter the pathogen
118
What are antibodies?
A protein produced in response to a specific antigen
119
What pathogen do antibiotics treat?
Bacteria
120
How might an antibiotic be useless against a bacteria?
The bacteria may be resistant to the antibiotic
