Evolution

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Diet and Exercise

Different amounts of Energy needed, based on metabolic rate

Balanced diet includes everything needed for a healthy body.

Energy taken in; Energy used; weight lost

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Weight problems

Starvation

underweight

deficiency disease (casued by lack of vitamins and minerals.)

fatigue

poor resistance

irregular periods

Obese

overweight

coronary heart disease

type 2 diabetes

high blood pressure

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Inheritance, exercise and health

Exercise

Regular exercise improves health as it increase metabolic rate and lowers cholesterol

Exercise increases amount of energy used by the body

decrease amount of stored fat

it also builds muscles and boosts metabolic rate

Inheritance

This effects the health factors, such as metabolic rate and cholesterol rate.

some people may inherit factors that effect their metabolic rate

some people may inherit factors that can effect their blood cholesterol

inherited factors that increase blood cholesterol levels can cause heart disease

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Pathogens,Microorganisms that cause disease

Pathogens and disease

reproduce rapidly, may produce toxins

viruses reproduce inside cells, damaging them

usually caused by bacteria and viruses

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Bacteria- cells

bacteria are very small cells

which reproduce inside your body

they make u feel ill by

damaging cells and producing toxins

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Viruses- not cells

viruses are not cells

they replicate themselves by invading your cells

and using machines to create copies

this will cause you cells to burst

releasing new viruses

the damaged cells make you ill

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Defense system

skin,hair and mucus stop a lot of viruses getting inside your body

and try to prevent microorganisms getting in to the body through cuts

small fragments of cells called platelets help clot blood quickly

if something does make it through you immune system kicks in

white blood cells travel in your blood and crawl into every part of you

when they come invading microbes they have 3 lines of attack:

consuming them white blood cells digest them

producing antibodies to kill invading cells, they are produced rapidly to kill viruses and bacteria

producing antitoxins which counteract toxins produced by the invading bacteria.

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Semmelweis

discovers how disease is passed from person to person

introduces hand washing in hospitals

called antiseptic which kills bacteria on the doctors hands

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Using drugs to treat disease

antibiotics cure bacterial diseases by killing bacteria

medicines such as painkiller relief symptoms, but don't kill pathogens

viruses are hard to destroy because they reproduce inside cells so there is a risk of damaging cells

antibiotics can kill bacteria but can't kill viruses

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Growing and investigating bacteria

Bacteria can be grown on agar jelly

All materials used must be sterilized

prevents unwanted microorganisms contaminating the culture

Uncontaminated cultures can be used for investigations of antibiotics and disinfectants

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Changing pathogens

bacteria can develop resistance to antibiotics through natural selection

new strains can cause epidemics or pendemics

epidemics- spread of disease in a country

pendemics- spread of a disease internationally

pathogens can change causing mutations

these can spread rapidly due to lack of immunity to new strains

strain- genetic variant microorganism

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Immunity/diseases

vaccines immunize against disease

vaccination works on both bacteria and viruses

vaccines contain dead or inactive pathogens

this encourages white blood cells to produce and remember the antibodies to destroy the pathogens

here immunization , vaccinating large numbers protects society from the risk of disease

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Natural selection

natural selections means the fittest organisms survive to breed

if a gene mutates the new characteristics may allow an organism to survive better

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Ecological & Evolutionary

comparing similarities and differences allow classifications of organisms to survive better

classification allows a evaluation of evolutionary relationships

Ecological

species with similar characteristics have similar genes because they share a recent common ancestor, so they're closely related. They often look alike and tend to live in similar types of habitats e.g whales and dolphins

occasionally, genetically different species might look alike too. E.g dolphins and sharks look pretty similar because they've both adapted to living in the same habitat. They have evolved from different ancestors

evolutionary trees show common ancestor and relationships between organisms. The more recent the common ancestor, the more closely related the two species.

Evolutionary

if we see organisms in the same environment with similar characteristics it suggests they might be in competition. E.g for the same food source

differences between organisms in the same environment. E.g dolphins swim in small groups, but herring swim in giant shoals

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Theories of evolution

Charles Darwin

Charles theory was only just accepted

his theory works like this

individuals within species show variation because of the differences in their genes e.g. some rabbits have big ears and some have small ones.

individuals with characteristics that bake them better adapted to the environment have a better chance of survival and so are more likely to breed successfully e.g big eared rabbits are more likely to hear a fox sneaking up on them, and so are more likely to live and have millions of babies small eared rabbits are more likely to end up as fox food

so, the genes that are responsible for the useful characteristics are more likely to be passed on to the next generation e.g all the baby rabbits are born with big ears.

his idea was against religious beliefs about how life on earth developed

Darwin couldn't give an explanation for why these useful characteristics appeared or how individual organisms passed on their beneficial characteristics to their offspring.

there wasn't enough evidence to convince many scientists because changes of organisms were not taught this topic

Lamarck

Lamarck argued that if a characteristic was used a lot by an organism then it would become more developed during its lifetime. e.g if a rabbit used its legs to run a lot to escape predators then its legs would get longer

he also believed that these acquired characteristics would be passed down on to the next generation e.g the rabbits's offspring would have longer legs.

his hypothesis was rejected because experiments didn't support his hypothesis however the discovery of genetics supported Darwin's idea because it provided an explanation of how organisms born with beneficial characteristics can pass them on.

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Mutations

a mutation is a change in an organisms DNA

most of the time mutations have no effect, but they do have benefits when producing useful characteristics

which will give the organism a better chance of surviving and reproducing

it is likely to be passed on to future generations by natural selection

the mutation will increase e.g some species of bacteria have become resistant to antibiotics due to a mutation

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Cloning

animals can be cloned by putting a nucleus in an empty egg and placed in a surrogate mother

a tissue culture could be made by taking some cells form the plant an growing them in special conditions

plant cloning can be made quickly and easily by taking cutting from good parent plants and plant them to produce genetically identical copies of the parent plant

the study of animal clones could lead to a greater understanding of the embryo and if aging and age related disorders

cloning could be use to help endangered species

also cloned animals may not be as healthy as normal ones e.g dolly the sheep

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Adult cell cloning

the nucleus which has a complete set of chromosomes of a cell is placed into and empty egg cell which is stimulated by an electric shock which make sit divide, and transplanted in to a host mother, creating a clone

scientist have used adult cell cloning to clone animals such as dolly the sheep

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Genetic engineering

enzymes are used to cut a gene from a chromosome and is inserted in another

genetic engineering transfers a gene for one organism to another to give a desired characteristic

the same method can be used to transfer useful genes into animals and plants, at an early stage of development

Genetically modified crops have had their genes modified e.g to make them resist viruses, insects or herbicides ( chemical used to kill weeds)

sheep have been genetically engineered to produce substances, like drugs in their milk that can treat human disease

genetic disorders like cystic fibrosis are caused by faulty genes this is being treated by gene therapy

Pros and cons of GM

Con's

the affect of GM can affect the number of weeds and flowers ( so the population of insects ) that live in crops. reducing farmland diversity

a lot of people think that GM crops are not safe also that this could develop allergies to the food

transplanted genes could get into the environment e.g herbicide resistance gene may be picked up by weeds, creating a new super weed

Pro's

GM crops can increase the yield of crop, making more food,

people living in developing nations often lack nutrients in their diets e.g golden rice is being tested which contains beta-carotene a lack of this can cause blindness

GM crops are being grown elsewhere ( not in the UK) without any problems

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Advantages of making choices about technology

produces medical drugs

crops are resistant to herbicides and insects

may provide cures for genetic disorders

Disadvantages of making choices about technology

"playing" God

could reduce or contaminate the gene pool

long term affects of eating GM crops aren't known

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Genetic and environmental differences

clones may have differences due to environmental causes

difference within species can be because of genetic factors due to differences in the genes they have they have inherited, and environmental factors such as diet and exercise

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Types of reproduction

sexual reproduction involves the joining of gametes from two parents leading to a variety of offspring's

clones- genetically identical copies of one parent

clones are produces during asexual reproduction, where no gametes join

Sexual reproduction

this where genetic information from two organisms is combined to produce offspring which are genetically different to either parent

the mother and father produce gametes e.g egg and sperm cells and animals

in humans , each gametes contain 23 chromosomes.

the egg and sperm then fuse together ( fertilization ) to form a cell with the full number of chromosome ( half from mother , half from father )

this is why the offspring inherits from both parents its received a mixture of chromosomes and its the chromosomes that decide how you turn out

this mixture of genetic material produces variation in the offspring.

Asexual reproduction

an ordinary cell can make a new cell by diving in 2.

the new cell has the exact same genetic information ( i.e genes ) as the parent cell

is asexual reproduction there is only one parent

there is no fusion of gametes

no mixing of chromosomes and no genetic variation between parent and offspring

the offspring are genetically identical to the parent, they are clones

describe how they work:

x-shaped chromosomes have two identical halves

so, each chromosomes splits down the middle

to form two identical sets of half chromosomes (i.e two sets of DNA strands) a membrane forms around each set

the DNA replicates itself to form two identical cells with complete sets of x-shaped chromosomes

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Inheritance

genes control characteristics of your body

genes are passed in gametes form parents to offspring

offspring have similar characteristics to their parents

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Genes, Chromosomes and DNA

most cells in you body have a nucleus. The nucleus contains your genetic material in the form of chromosome

the human cell nucleus contains 23 pairs of chromosomes. There are two No. 19 chromosomes, two No. 12's, two No. 3's etc

chromosomes carry genes. Different genes control the development of different characteristics. e.g hair color

a gene is a short length of the chromosome which is quite a long length of DNA

the DNA is coiled up to form the arms of chromosomes

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Carbon cycle

the carbon cycle is powered by photosynthesis. Co2 is removed from the atmosphere by green plants and algae, and the carbon is used to make carbohydrates, fats and proteins in the plants and algae

some of the carbon is returned to the atmosphere as Co2 when the plants and algae respire. Some of the carbon becomes part of the fats and proteins in animals when the plants and algae are eaten. The carbon then moves through the food chain

some of the carbon is returned to the atmosphere as Co2 when the animals respire

when plants, algae and animals die, other plants ( detritus feeders ) and microorganisms feed on their remains. When these organisms respire, Co2 is returned to the atmosphere.

animals produce waste, and this too is broken down by detritus feeders and microorganisms. Compounds in the waste are taken up from the soil by plants as nutrients - they're put back in the food chain again.

some useful plants and animal products, e.g wood and fossil fuels, are burnt by combustion. This also releases Co2 back into the air.

so the carbon is constantly being cycled - from the air, through food chains and eventually back out into the air again.

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Decay processes

organisms take nutrients from the environment which are returned when they die

decay is started by detritus feeders who produce waste material that are then eaten by microorganisms called decay organisms

decay happens quicker in warm, moist aerobic conditions

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Energy transfers

less energy is available at each stage of the food chain as it is lost through movement, waste and into the surroundings

the rest is used for growth

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Pyramids of biomass

biomass at each stage of the food chain is less that the previous stage

biomass- amount of dry living mass in an organism

main source of energy for organisms is the suns radiation

green plants turn the light energy to chemical energy during photosynthesis

each bar on a pyramid of biomass shows the mass of living material at that stage of the food chain- How much all the organisms would weigh at each level if you put them all together.

so the one for fox above would have a big biomass and the hundreds of fleas would have a very small biomass. Biomass pyramids are practically always pyramid shaped

Constructing pyramid of biomass

the bar along the bottom of the pyramid always represents the producer i.e plant

the next bar will be the primary consumer ( the animal that eats the plant )

then the secondary consumer ( the animal that eats the primary consumer )

and so on up the food chain

Interpreting pyramid of biomass

you should be aware that the grass is older than the grass hopper

so thousands of grasshoppers are feeding on the grass

and quite a lot of mice are eating the grasshoppers

and a few snakes are eating the mice

biomass and energy are still decreasing as you go up the levels

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Recycle and organic waste

recycling waste reducing landfills and methane

and recycles nutrients in the waste

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Adaptation in animals

adaptations help and animal survive

animals in cold climates are usually large with a small surface area;

volume ratio, and vice versa for hot climates

coat color may provide year round camoflage

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Adapt and survive

some microorganisms are adapted to live in the most extreme environments

organisms get necessary material for survival form their surroundings and other organisms

organisms are adapted to survive in the condition they normally live

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Adaptations in plants

plants lose water vapor from stomata on the leaf's surface

to conserve water plants reduce the surface area of leaves, store water have extensive root systems.

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Competition in animals

animals compete for ; food, water and mates

the best adapted animals are good competitors

Competition in plants

plants complete for; water, light, space and nutrient and mineral ions from the soil

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Measuring environmental change

environmental changes the distributions of organisms

changes can be caused by living factors, arrival of a new predator or disease, or non-living factors, temperature and rainfall

environmental changes can be measured with non-living indicators such as thermometers and rain gauges

organisms, indicator species, can be used to disclose pollution levels

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Impact of change

distribution of organisms can be affected by living and non-living factors

data on the effect of environmental change isn't always easy to interpret

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Drugs

both legal and illegal drugs may harm your body

drugs- a chemical that affects your behavior or thoughts

chemicals in cannabis may cause mental illness in some people

cocaine and heroine is very addictive, and you may suffer from withdrawal symptoms when trying to stop taking them

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Legal and illegal drugs

medicinal drugs used to control disease and can only be prescribed by a doctor

recreational drugs- used only for pressure and affect the brain and nervous system

recreational drugs can be legal like caffeine or alcohol or illegal like cannabis or heroin

impact of legal drugs is greater than illegal as they are more readily available

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Does cannabis lead to hard drugs?

obtaining cannabis from dealers may put people in contact with harder drugs

chemicals in cannabis can cause mental illness particularly in teenagers

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Drugs in sport

some athletes use illegal performance enhancing drugs such as steroids to give them an unfair advantage in competition

moat would consider this unethical

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Developing new medicines

placebo- don't contain a drug, are used to see if drugs do have an effect

double blind trials- neither doctor nor patient knows which is the drug and which is the placebo, to remove bias

drugs are tested in labs, on animals and in clinical trial on healthy and ill patients

thalidomide, a sleeping pill, was found to cure morning sickness but caused birth defects so now treats leprosy

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How effective are medicines?

statins lower cholesterol levels and have lowered heart disease by 40%

double blind trials should be used to test non prescribed medicines to remove bias

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Responding to change

nervous system allows reaction to surroundings

receptors in sense organs detect external stimuli

impulse sent along sensory neurone to the brain

brain coordinates response, which is sent down to the motor neurone

effector then responds

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Reflex actions

reflex actions are automatic responses to a stimulus and usually keeps us out of danger

between neurons there are synapses that use chemicals to pass the impulse over the gap

reflex arc is similar to normal response, but instead of going to the brain, the impulse is processed by a relay neurone in the spinal chord

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Hormones and the menstrual cycle

oestrogen- produced by the ovaries and it inhabits the production of FSH to stimulate the production of LH and the womb lining

lutenising hormone (LH)- made in the pituitary gland and it stimulates the release of the matured egg

follcile stimulating hormone (FSH)- made in the pituitary gland and causes and egg to mature and stimulates the production of oestrogen

menstrual cycle lasts 28 days with ovulation at 14 days

Nerves:

very fast action

act for short time

act on a very precise area

Hormones:

slower action

act for a long time

act in a more general way

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Artificial control of fertility

the contraceptive pill may contain oestrogen and progesterone to inhibit FSH

FSH can be given to help an infertile woman produce eggs

Fertility treatments

Advantages

reduces family size

women can plan pregnancies

couples that couldn't have children before can now

Disadvantages

pill can cause effects

IVF is expensive

embryos maybe destroyed

ethical and religious implications

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Controlling condition

internal conditions of the body must stay constant

controlled by the nervous system and hormones

water, ion content temperature and blood sugar levels are controlled

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Hormones and the control of plant growth

plants respond to light, phototropism, gravity, geotropism and moisture, hydrotropism

auxin is the plant hormone that controls light and gravity

in a root the auxin gathers on the underside, and makes the plant where there is less auxin to grow more, bending the root towards the ground

in a shoot auxin gathers on the underside and makes the part where there is more auxin to grow, bending the shoot away from the ground

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Using hormones

misuse of plant hormones could affect the environment

can have side affects

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Menstrual cycle

when the bleeding starts- the uterus lining breaks down for about four days

the lining of the uterus builds up again- from day 4 to day 14, into a thick spongy layer of blood vessels are ready to receive fertilized egg

an egg released from the ovary at day day 14

the wall is then maintained for about 14 days until day 28 if no fertilized egg has landed on the uterus wall by day 28, the lining starts to break down and the whole cycle starts again