PAPER 2 Flashcards
What is homeostasis
The regulation of the conditions inside your body to maintain a stable internal environment
What three main components make up your automatic control systems?
Receptors, coordination centres and effectors
Why do the internal conditions of your body need to be regulated?
Your cells need the right conditions to function properly including the conditions for enzyme action.
What is negative feedback
When your body detects an imbalance in the levels of something (water or glucose) and so sends a signal to do the opposite
What is a sensory neurone?
Neurones that carry information as impulses from the receptors to the CNS
What is a motor neurone?
A neurone that carries a signal from the CNS to effectors
What is an effector?
A part of the body (muscles and glands) that provides a response to nervous impulses
What is a receptor?
A cell that detects a stimulus
Give 2 examples of receptors
Taste receptors on the tongue
Sound receptors in the ears
How are neurones connected
Synapses
What is a synapse?
A link between two neurones which transfers a signal by chemicals that diffuse across the gap
Whats the purpose of a reflex?
To prevent injury
Give 3 factors that can affect reaction time
Age
Gender
Drugs
How would you measure the effect of caffeine on reaction time?
The ruler drop test, done once without caffeine and repeated again with it
Why might you use a computer to measure reaction time?
It is more accurate, can measure in miliseconds etc
It is more precise, removes human error
Removes the posibility of predicting the drop
What is the pituitary gland?
The ‘master gland’ that controls other glands in the endocrine system
What does the thyroid do?
Produces thyroxine
What does thyroxine regulate? (3)
Heart rate
Temperature
Metabolism
What does the adrenal gland do
Produces adrenaline
What does adrenaline do?
Prepares a ‘fight or flight’ response
What does the pancreas do? (Hormones)
Produces insulin to regulate blood glucose level
What do ovaries do?
Produces oestrogen
What do the testes do?
Produces testosterone that controls puberty and sperm production
Name three differences between nerves and hormones
Nerves are very fast - hormones slower
Nerves are short term - hormones long term
Nerves act on a very precise area - hormones more general
What two hormones are involved in the control of blood glucose levels?
Insulin and glucagon
What happens when blood glucose is too high?
Insulin is added
What happens when blood glucose is too low?
Glucagon is added
What is type 1 diabetes?
When your pancreas produces little or no insulin
What is type 2 diabetes?
When someone becomes resistant to their own insulin
How can you help type 1 diabetes? (3)
Taking injections of insulin
Limit your intake of simple carbohydrates
Do regular exercise
How can you help type 2 diabetes? (2)
Eat a carbohydrate controlled diet
Get regular exercise
What is stage 1 of the menstrual cycle?
The lining of the uterus breaks down for around 4 days
What is stage 2 of the menstrual cycle?
Uterus lining builds back up again into a spongy layer of blood vessels
What is stage 3 of the menstrual cycle?
Ovulation (around day 14)
What is stage 4 of the menstrual cycle?
Uterus lining maintained. If no egg has fertilised, the lining breaks down and the process restarts
What does FSH do and where is it produced? (3)
Pituitary gland
Causes an egg to mature
Stimulates the ovaries to produce oestrogen
What does LH do and where is it produced? (2)
Produced in the pituitary gland
Stimulates ovulation
What does oestrogen do and where is it produced? (4)
Produced in the ovaries
Causes uterus lining to grow
Stimulates LH release
Inhibits FSH release
What does progesterone do and where is it produced? (4)
Produced in the ovaries after ovulation
Maintains uterus lining while present
Inhibits the release of LH
Inhibits FSH release
How can oestrogen be used as contraception?
It prevents FSH release so egg development and production stop
How does progesterone prevent pregnancy?
It creates thick mucus that prevents any sperm getting through
How is the combined oral contraceptive pill different to a progesterone only pill? (2)
It also contains oestrogen
It has more side effects
Name 6 types of female hormone contraception
Combined pill
Progesterone only pill
Patch
Implant
Injection
IUD
How does a contraceptive implant work?
Constantly releases progesterone
How does a contraceptive patch work?
It is stuck to the skin for about a week and contains oestrogen and progesterone
How does a contraceptive injection work?
Contains progesterone, lasts 2 - 3 months
How does an IUD work?
Either releases copper to kill sperm or progesterone. It is inserted into the uterus. Also prevents implantation.
What 3 ways can you prevent pregnancy that arent barrier or homone based?
Sterilisation - (male or female vasectomy)
Natural methods - (not having sex on days where an egg is released)
Abstinence - (dont have sex)
What are the pros and cons of using FSH and LH to increase fertility?
Can allow you to have a child
Can stimulate too many eggs
Doesnt always work which can become expensive
How does IVF work?
It involves collecting eggs from the woman and fertilising them with the man’s sperm. It could also be an injection of the male sperm if the male has low sperm count.
What stage of development is the embryo transferred to the woman during IVF?
When the embryos are tiny cells of balls one or two are inserted into the uterus
How is egg collection in IVF made easier?
FSH and LH are given to stimulate more eggs to be produced
What are some cons of IVF?
Multiple births can happen
It is not very effective (26% in the UK)
It is not only emotionally stressfull but physically for the woman as there can be side effects
Why might some people be against IVF?
It creates unused embryos that are destroyed
Genetic testing could lead to the selection of preffered characteristics
What else does thyroxine do other than control metabolism?
Stimulates protein synthesis
What stimulates the prodiction of thyroxine and how can this be manipulated
TSH
Negative feedback is used to control TSH levels which subsequently controls thyroxine levels
How is dna found in the body?
In long structures, chromosomes
What is a gene?
A small section of dna
Def genome
The entire set of genetic material in an organism
Why is it really important to understand the human genome?
You can link genes to certain types of diseases
You can find out which genes are linked to inherited diseases
Scientists can track the migration of humans
How are gametes produced?
Meiosis
How does sexual reproduction differ to asexual? (In terms of the offspring)
Sexual reproduction provides offspring which are genetically different to each parent
What does it mean that asexual reproduction only comes from one parent?
All offspring are genetically identical
How does asexual reproduction happen?
Mitosis
Describe the process of meiosis
- Cell duplicates its chromosomes
- The cell divides and the chromosomes line up in the centre
- The pairs of chromosomes are then pulled apart
- The chromosomes line up again and the cell divides
What process does an embryo use to grow after gamete fusion?
Mitosis
What is genotype?
The combination of alleles you have
What is your phenotype?
The charictaristics that you have
What kind of allele is cystic fybrosis
Recessive
What kind of allele is polydactyly
Dominant
What are three reasons against embryonic screening?
It implies people with genetic disorders are undesireable
Could lead to people choosing desireable characteristics. Designer babies
Its expensive
What are three reasons for embryonic screening?
Helps prevent suffering
Treating disorders costs governments and taxpayers lots of money
There are laws to stop it going to far. You can’t even chose the sex of your baby. (Unless for health reasons)
What two ways can an organisms phenotype be affeced?
Its genotype
Interactions with the environment (most easily spotted in plants)
Def mutation
Changes to the genome
What effect do most mutations have on phenotype?
None
Give an example of a mutated gene that affects phenotype
Cystic fybrosis
What does cystic fibrosis do?
Produces excess mucus in the lungs and digestive system that make it harder to breathe and digest food.
Define the theary of evolution
All of todays species have evolved from life forms that first started to develop 3 billion years ago
Def survival of the fittest
The organisms with the most suitable characteristics for the environment would be more successful competitors and more likely to survive
What is the process called where a completely new species is formed?
Speciation
How does speciation happen?
When populations of the same species become so reproductively isolated that they can no longer interbreed
Give 5 reasons a species may become extinct
The environment changes too quickly (destruction of habitat)
A new predator kills them (can be humans)
A new disease kills them
They cant compete with another species for food
A catastrophic event happens (e.g. giant meteor rip dinosaurs)
How is selective breeding done today? (4 examples)
Animals bred to produce more meat or milk
Crops with disease resistance
Dogs with gentle behavior and certain features
Decorative plants with big or unusual flowers
How do you do selevctive breeding (4 steps)
Select the characteristics you want from your stock
Breed them together
Select their best offsprind and breed
Continue process over many generations
What is the main drawback of selective breeding?
It reduces the gene pool (number of different alleles in a population)
Def inbreeding
When animals or pants are bred too close together (gentically) and the gene pool reduces
What weakness do inbred organisms have?
A fatal disease could kill all of your stock due to little genetic variation
How do you carry out genetic engineering? (3)
- Isolate the useful gene using enzymes and insert it into a vector
- The vector is usually a virus or bacterial plasmid
- Introduce the vector to the organism
What can genetic engineering be used for? (4)
Bacteria have been engineered to produce insulin
Geneticall modified crops have been developed which are resistant to diseases and herbicides etc and have a higher fruit size usually
Sheep have been modified to produce drugs in their milk
Inserting healthy genes into people with inherited diseases. (Gene therapy)
What are some cons of gm crops? (3)
Concern that wild flowers and insect populations are greatly reduced
People are concerned they are not safe and have negative effects on human health
Comcerns that genes may get out into the wild and create some sort of superweed
What are some pros of gm crops?
Characteristics can increase the yield
Crops can be engineered to contain missing nutrients
GM crops are already grown in some places without issue
What three ways can fossils be made?
From gradual replacement by minerals
From casts and impressions (e.g. imprinting in clay)
From preservation in places without decay (amber, tar, glaciers, peat bogs)
Why dont humans know how life began?
Early life forms were soft-bodied so the fossil record is incomplete
Fossils that formed many millions of years ago may have been destroyed by geologicalactivity (tectonic plates etc)
What is the danger of MRSA?
It is a superbug that can be fatal if entered into the bloodstream
What are the 7 groups of the linnaeus system in order?
Kingdom
Phylum
Class
Order
Family
Genus
Species
What are the three domains?
Archaea (primitive bacteria)
Bacteria (true bacteria, biochemically different to archaea)
Eukaryota (very broard range of organisms)
What is the first and second part of a binomial name?
The genus
The species
Def stable community
Where all the populations in a community remain fairly constant
Examples of abiotic factors (7)
Moisture levels
Light intensity
Temperature
Carbon dioxide level
Wind intensity and direction
Oxygen level
Soil pH and mineral content
Exmples of biotic factors (4)
New predators
Competition
New pathogens
Food availability
What are the three different types of adaptations
Structural
Behavioural
Functional
Give 3 examples of adaptations to animals
Arctic foxes have white fur to camoflage and for sneak attacks
Animals like whales (cold env) have thick layers of fat and low sa:v to help retain body heat
Animals like camels (hot env) have thin layers of fat and large sa:v to help lose body heat
One example of a behavioural adaptation
Swallows migrate to warmer climates to avoid cold conditions
Give 2 examples of functional adaptations
Desert animals conserve water by producing little sweat and concentrated urine
Brown bears hibernate in winter to avoid hunting when there isnt much food
Def extremophile
An organism adapted to live in extreme environments such as high temperature, pressure or salt concentration
What are the first 4 levels of a food chain called?
Producer
Primary consumer
Secondary consumer
Tertiary consumer
How can you measure organism distrubution? (2)
Quadrats
Transect lines
How would you estimate percentage cover of something like grass over a given area?
Use quadrats and count how many quadrats are over half covered. Then divide by the amount of squares and calculate percentage.
Briefly describe the water cycle (6)
Water evaporates or transpires
Water falls as precipitation
Some water is absorbed by plants, soil and drank by animals
Water is released as waste
Unabsorbed water runs off into rivers
Water runs into the sea and cycle restarts
How are elements cycled back through the food chain
Decay
Briefly decribe the carbon cycle (7)
CO2 removed from the atmosphere by photosynthesis
Plants and algae respire, returning it
Plants get eaten, CO2 moves through food chain
Animals respire, returning CO2
When they die, microorganisms feed and respire
Animals produce waste
Combustion
Def biodiversity
The variety of different species of organisms on Earth or in an ecosystem
How is modern waste affecting water?
Sewage and chemicals pollute lakes and rivers. E.g. herbicides and pesticides running into water.
How is waste affecting land?
Toxic chemicals pollute the land
Nuclear waste makes some sites uninhabitable
Lots of waste dumped into landfill sites
How is waste affecting the air?
Smoke and acidic gases pollute the air
Chemical (such as sulfur dioxide) cause acid rain
What two gases trap energy from the sun?
Carbon dioxide and methane
Give 4 consequences of global warming
Seawater can expand and ice can melt causing rising sea levels. Leads to flooded areas and habitats.
Distribution of wild animals and plants may change. Could increase and decrease
Changes in migration patterns
Biodiveristy reduced and extinction increased
What 4 ways do humans commonly use land?
Building, farming, quarrying, landfilling
Why might deforestation take place?
To clear land for farming
To grow crops for biofuels
For timber
What 3 problems does deforestation cause?
- Less CO2 intake -carbon taken in from the atmosphere is reduced
- More CO2 in the atmosphere - releasing locked up carbon in burning or digestion by microorganisms
- Less biodiversity - removal of habitats can cause extinction
How does destroying peat bogs have a negative environmental affect?
They contain decayed plants that cause microorganisms to release CO2 upon digestion.
CO2 also released when peat is burned as fuel
It reduces habitats and decreases biodiversity
Give 5 examples of programs to protect ecosystems and biodiversity
Breeding programs for endangered species
Programs to regenerate rare habitats
Reintroduce hedgerows for CO2 and habitats
Introduce regulations for deforestation
Reduce landfill waste
How can it be hard to protect biodiversity? (4)
It costs money to setthings up and maintain programs
It can cost local livelihood e.g. employees of timber companies
Some organisms are pests to farmers e.g. locusts and foxes so need to be killed
Development is important such as houses in developing countries needs land
