Biology

Energy comes from food

Your diet must provide energy

You need: 

• Carbohydrates > release energy 
• Fats > keep you warm & release energy 
• Protein > helps growth & cell repair & replacement
• Fibre > to keep your digestive system running smoothly 
• Vitamins and Minerals > keeps your bones, skin, blood generally healthy

A balanced diet contains water, carbs, fats, minerals, vitamins, protein and fibre.

> People with a higher proportion of muscle too fat have a higher metabolic rate.

> Taller people generally have a higher metabolic rate. 

> Men generally have a higher metabolic rate. 

> Exercise  boosts your resting metabolic heart rate. 

Metabolic rate increases with exercise. 

> Builders needs more energy than an officer worker.

  > When you exercise you need more energy so you metabolic rate goes up.

No exercise = less energy = less fat and carbs in your diet

More exercise = more energy = more fat and carbs in your diet 

Malnutrition 

People who have too much or too little in a diet.

E.G. Obesity, Scurvey, Rickets, Anorexia

Malnourished

People whos diet is badly unbalnced whether tehy are thin or fat. 

Eating to much can lead to obesity... 

• Excess carbohydrates and fat
• Most common in delevoped copuntries 
• Diagnosed when you are 20% over teh maxuim body mass 
• Hormonal problems could cause it (bad diet, overeating, lack of exercise) 
• Encourages arthritis, high blood pressure, type two diabetes, heart diseases and maybe cancer

Eating to much can lead to obesity... 

• Excess carbohydrates and fat
• Most common in delevoped copuntries 
• Diagnosed when you are 20% over teh maxuim body mass 
• Hormonal problems could cause it (bad diet, overeating, lack of exercise) 
• Encourages arthritis, high blood pressure, type two diabetes, heart diseases and maybe cancer

Lack of food ... 

> Most common in developing countries

> You're effect vary from what food you are lacking

• Common effect are slow growth in children
• Poor immune system
• Fatigue
• Poor resistance to infection
• Irregular period for women 

>Deficiency diseases if you lack minerals and vitamins - scurvy (not enough vitamin C)

EXERCISE + BALANCED DIET = HEALTHY

Exercise:  

• decreases fat
• builds muscle 
• boosts metabolic rate
• more immune to diseases
• less likey to be obese

People can be fit but not healthy

e.g. people can be slim and fit but be malnourished as they have a imbalanced diet 

It's just about what you eat and how much you exercise it can depend of inherited factors too... 

• Some people inherit under active thyroid gland which lowers metabolic rate leading to obesity.
• High cholesterol will increase the chances of heart disease.

• Energy is measured in kilojoules (kJ), or calories (kcal) to many calories leads to obesity.
• "of which saturates" means there is more fat in your food and your cholesterol levels can raise. 
• Food which contains Calcium is good as it is a mineral.
• Things which contain sodium are bad for you as they contain salt which can lead to high blood pressure.

Lifestyle effects heath because ... 

It depends on what you do 

and 

What you eat

Bacteria:

• very small cells                            
• reproduce rapidly
• make you feel ill
• release toxins

Viruses:

• NOT CELLS
• smaller than bacteria
• replicate themselves
• invade your cells
• produce copies if themselves
• they burst and make you feel ill

- skin, hairs, mucus stop a lot of nasties getting in

- platelets try to stop micro-organisms getting through cuts by clotting blood quickly (less platelets = slow clot)

- white blood cells patrol the blood looking for microbes

IF THEY FIND ANY THEY HAVE THREE LINES OF ATTACK...

Engulfing them...

Producing antibodies...

every invading cell has a unique antigen and when white blood cells find them they create antibodies to lock onto them, they won't fit onto another combination, they produce rapidly to fight the disease

Producing antitoxins...

Antibodies:

the things that are produced by white blood cells to lock onto the unique code

Antigen:

the unique code on each infection

You inject small amounts of dead or inactive microorganisms that carry antibodies

Pros

• control diseases
• prevent epidemics

Cons

• sometimes don't work
• bad reactions

SEMELWEIS

1840

women dying in childbirth

he noticed doctors spreading diseases from not washing hands

told them to was hands

death dropped from 12% - 2%

Recently death rate from bacterial diseases (pneumonia) has dropped dramatically, but the over use of drugs has increased the likelihood of people being antibiotic - resistant strains. People who get infected by them can't get rod of them very easily.

Antibiotic resistance is a big problem and had been encouraged drug companies to develop new and effective antibiotics.

Meanwhile.. 'superbugs' are becoming more common.

A stimulus is a change in the environment.

Sense organs:

• eyes - light
• ears - sound, balance
• nose - chemicals
• tongue - taste
• skin - touch, pressure, pain, temperature

SENSORY NEURONE ~ carries signals as electrical impulses from receptors to the CNS(central nervous system)

RELAY NEURONE ~ carries signals from sensory neurones to the motor neurone

MOTOR NEURONE ~  carries signals from CNS to the effectors

CNS

• where all information from sense organs is sent
• where reflexes and actions and co-ordinated
• uses the brain and spinal cord
• neurones transmit (electrical impulses) information to and from the CNS
• instructions are sent from CNS to effectors which respond accordingly

1. Stimulus

2. Receptor

3. Sensory Neurone

4. Relay Neurone

5.Motor Neurone

6. Effector

7. Response

Hormones are:

• chemical messengers which travel in the blood to active target cells

• carried around in the blood plasma

• produced by glands

• Long lasting effects

If the response is quick = nerves

If the response last a long time = hormones

Nerves

• fast
• short time
• precise area

Hormones

• slower
• long time
• general area

Day 1 - Lining of the uterus breaks down

Day 4 - Uterus lining builds up

Day 14 - Egg released

Day 28 - If no fertilised egg has landed the process starts again

FSH

• produced by pituitary gland(brain)
• causes egg to mature
• starts ovaries producing oestrogen

Oestogen

• produced in the ovaries
• cause pituitary to produce LH
• stops production of FSH

LH

• Produced by the pituitary gland(brain)
• stimulates the release of an egg

Oestrogen prevents the release of an egg, if you take it every day to keep it permanently high it will inhibit FSH and will stop egg development and the production stops.

Progesterone - thick cervical mucus which prevents any sperm getting in.

the pill was first made in the 1950's and contained high levels of oestrogen and progesterone

concerns about blood clotting

now has lower doses of oestrogen so has fewer side effects

+99% effective

+reduced risk of some cancers

-not 100% effective (slight chance of still getting pregnant

-side effects liek headaches and irregular periods

-doesn't protect against STD's

Some women have levels of FSH that are too low to cause their eggs to mature. This means that no eggs are released and the women can't get pregnant.

FSH and LH can be injected to stimulate egg release in their ovaries.

 + helps a lot of women to become pregnant

 - expensive and doesn't always work

 - to many eggs could be released = twins & triplets

> collect eggs

> fertilise in the lab with sperm

> grow into embryos

> when they are tiny balls of cells transfer to uterus

+ a child is made

- increase cancer risk

- reactions to hormones (vomiting, stomach pains)

- multiple births if more than one embryo grow into a baby > miscarriage/still birth

Auxin -  It is a plant hormones which controls growth near the tips, shoots and roots. It controls growth in response to light, gravity and moisture. Produced in the tips and moves backwards to stimulate the cell elongation  (behind tips). If you the tip is removed no auxin is available and may stop growth. If more auxin is used it promotes growth in the shoot but inhibits in roots. 

A     AUXIN
S     STIMULATES
S     SHOOTS

A     AUXIN
I      INHIBITES
R    ROOTS

Shoots grow towards light

1. more auxin accumulates on the side in the shade

2. it makes cells grow faster on the shaded side so the shoot bends towards the light

Shoots grow away from gravity

1. shoot tip grows sideways and more auxin is in the tip underneath

2. it grows faster and bends upwards

Roots grow towards gravity

1. roots growing sideways will have more auxin underneath

2. has more auxin so inhibits growth so cells on top grow faster and roots bend downwards

Roots grow towards moisture

1. more auxin is produced on the side which has more moisture

2. it will inhibit growth on that side and bend in that direction towards the moist

Agriculture

• Weed killers only kill broad leaves plants by disrupting normal growth
• Plant cutting don't always grow in soil so adding rooting powder containing auxin will reproduce plants rapidly. Cloning them very quickly

Homeostasis means that's all functions in your body which try to maintain  "constant internal environment"

Ions are taken into the body by food and then absorbed into the blood.

If food contains too much of any ion they will be removed. (Salty meals will contain to much) 

Some ions are lost in sweat- also tastes salty!

The kidneys will remove excess from the blood and then get rid of it via urine

Water 

The body needs a constant balance of water going in than it going out. So water is taken into the body as food and drink an dis lost through sweat, urine, breath and faeces. 

Cold day... no exercise = no sweat = more urine = pale urine (more diluted)

Warm day... exercise = sweat a lot = urine is darker (more concentrated) 

                                                         = more water lost by breathing more

Body Temperature: 

                            Enzymes work best at 37'C. This is what your body tries to                                       maintain.Your brain is sensitive to blood temperature so it                                         receives messages from the skin.

Blood sugar levels: 

                          Carbohydrates puts glucose into the gut. Normals metabolism                                 cells remove glucose from the gut but also vigorous exercise                                   removes much more. Insulin helps to maintain the level of glucose                           in your body.

Drugs.. 

• change your body chemistry - become addicted, addicts can suffer withdrawal symptoms(unpleasant) E.g heroin, cocaine, nicotine & caffeine
• medical - non-prescription (paracetamol), prescription (morphine) can become dangerous
• Recreational - a drug used non-medically for fun
• Performance-enhancing - can improve a persons performance in sport

    + own decision 

    + Drug-free sport isn't really as different athletes have to use different facilities and coaches    etc.

    - health problems (negitive effects-high blood pressure)

    - cheating

    - athletes may not be informed of full health risks

Statins are prescribed drugs used to lower the risk of heart and circulatory disease. They say statins lower cholesterol (made in the liver for a healthy heart you need) 

Research findings aren't always perfect...

Cannabis is an illegal drug. they wonder whether chemicals in cannabis smoke cause mental health problems. So no body is sure!

HIGH HDL >  good cholestrol

LOW LDL  >  bad cholestrol

Desert

Animals have adapted to save water and keep cool(large surface area/volume). they use less water and produce small amounts of concentrated urine. Good in hot conditions and camouflage. 

Plants have adapted to little water supplies (small surface area/volume. Their water is stored in tissues. They maximise water with absorption by have wide shallow roots or deep roots to gain water from underground.

Arctic animals have adopted to reduce heat loss(small surface area/volume). They are well insulated and camouflaged.

Some plants and animals to protect themselves from predators. Plants have amour - like rose(thorns), cacti(sharp spines), tortoises (shells). Others produce poisons like bee stings. And some warn off predictors by having warning colours like wasps. 

Microorganisms have made adaptation so they can live in a wide range of places like in salty lakes, high pressure areas and hot volcanoes. These type of animals are bacteria and they are call extremophiles. 

Organisms compete for resources to survive in the wild.

Plants- light > space > water > minerals

Animals- space > food > water > mates

Plant environment changes all the time. The living factors are:

• infections
• diseases
• predators
• prey or food sources
• competitor

The non-living factors are:

• temperature
• rainfall
• air/water pollution

Environment changes the population in three ways: 

Increases:

Prey increases > more food > more survive

Decreases:

less food > more diseases 

Distribution:

Temperature rise 

Organisms that are sensitive to changes are known as indicator species. 

Air pollution can be managed by looking at particular types of lichen... they are sensitive to sulfur dioxide in the atmosphere. The number of lichen indicates how clean the air is. 

Lots of lichen = Clean air 

Mayfly larvae are good indicator for water pollution because they are very sensitive to the concentration of dissolved oxygen. 

Mayfly in a river = Clean water

Other species like rat-tailed maggots and sludge worms have adapted to live in polluted conditions. 

Rat-tailed maggots and sludge worms = high level of water pollution

Satellites  measure

•  temperature of the sea
•  amount of snow and ice cover

 Automatic weather station measure 

• Atmosphere temperature

Rain Gauges measures

• average rainfall change year on year

Dissolved oxygen meters measures 

• water pollution changing

Biomass is the mass of a living material.

There is less energy and biomass every time you move up a food chain stage andusually fewer organisms. 

Producer 

Primary consumer

seconday consumer

(plants at the bottom)

Energy disappears ... 

                        Sun energy is almost all the energy on the earth. 

Green plants use a small percentage of the light to make food during photosynthesis. It is a stored substance which makes it's way up the food chain as animals them and each other. 

               Respiration supplies the energy for all life processes                                             including movement. Most of this energy is lost to the                                          surrounding as heat. This is especially true for mammals                                      and birds whois bodies need to keep at a constant body temperature. 

                Some of teh material whuich makes up plants and aniamls is inedible                     (bone) so it  doesn't pass the next stage of teh food chain. 

                                       Material and energy are also lost as waste materials.

• Elements are cycled back into the start of the food chain by decay.
• Plants turn elements into carbohydrates, proteins and fats. They are returned to the environment through organisms waste.
• In a stable community the materials are taken out and used are balanced by those that are put back in.

Composts need:

> Heat 

> Oxygen 

> Moist 

The whole thing is powered by photosynthesis. Some carbon is returned by plants, microorganisms and animals respiring and combustion.

Different genes cause genetic variation: 

Plants and animals have similar characteristics to parents because it depends on what genes you inherit, some from mum and some from dad. The combining of genes causes genetic variation.

Some characteristics are only determined by genes. These are hair colour, eye colour and blood group.

 Any differences that have been caused by weather, light and temperature are called environmental variation.

Most characteristics are determined by a mixture of genetic and environmental factors. 

For example... the maxium height for a plant or animal to grow depends on it genes, but whether it actually grows tall depends of the environment (how much food it gets).

Most of the calls in your body have a nucleus. They contain you genetic material in the form of chromosomes. The human nucleus has 23 pairs of chromosomes. A gene is short length of chromosome... which makes a long length of DNA. 

There  are different versions of the same gene, which give different versions of characteristics, like blue or brown eyes. The different versions are called alleles instead of genes.

C-G       A-T       G-C       T-A

• Sexual reproduction involves to parents, a male and female with two sex cells.
• The offspring will inherit both genes and will not look like either of them. 
• They are genetically different. 
• The mother and father produce gametes.
• In humans, each gametes has 23 chromosomes - half the number of chromosomes in a normal cell.
• The egg and sprem fuse together to form a cell with a full set of chromosomes.

This is why there is a variety which is a great advantage because it makes it likely that some of the offspring will survive difficult conditions using mutations.

Genetically Identical Cells

1. An ordinary cells can make a new cell by dividing in two. 

2. The new cell will have exactly the same genetic information as the parent.

3. There's no fusion of gametes.

4. No mixing of chromosomes.

5. No genetic variation. 

6.They're clones

 This is how plants and animals grow and produce replacement cells. 

The simplest way to clone a plant involves taking a cutting.

• A branch from the parent plant is cut off, its lower leaves removed and the stem planted in damp compost. 
• Plant hormones are often used to encourage new roots to develop. 
• The cutting is usually covered in a clear plastic bag at this stage to keep it moist and warm. 
• After a few weeks, new roots develop and a new plant is produced.
• The method is easy enough for most gardeners to do successfully.

1. Small amounts of parent tissue or a number of cells are taken
2. The plant material is transferred to plates containing sterile nutrient agar jelly
3. Plant hormones are added to stimulate the cells to divide
4. Cells grow rapidly into small masses of tissue
5. More growth hormones are added to stimulate the growth of roots and stems
6. The tiny plant lets are transferred into potting trays where they develop into plants

Tissue Culture 

A few plant cells are put in a growth medium with hormones, they grown into new plants  = clones of parent plant. 

This can be done very quickly in very little space. This can also be done all year round.

Cuttings 

:D - Very cheap to produce clones 

:( - Reducing gene pool 

:( - Takes a long time 

:( - Only a certain number of shoots available

:( - Only possible on a small scale 

Tissue Culture

:D - Never run out of cells 

:D - Quick

:D - Done all year round 

:D - Little space needed 

:( - Expensive 

:( - You have to keep the cells in sterile conditions 

:( - Cells get infected easily 

Stage 1 - Remove a mature egg from a female 

Stage 2 - Remove the nucleus with a syringe

Stage 3 - Remove an ordinary cell (any part of the body except the ovaries)  from a                       another animal

Stage 4 - Remove the nucleus. Throw away CELL > Inject the nucleus from Stage 3                      into Stage 1's cell

Stage 5 - The egg now contains a full set (2 = 46) chromosomes and begins to develop

Stage 6 - Implant the embryo into uterus of a surrogate animal 

Stage 7 - The baby is born and her mother is the mother which donated the nucleus.                      The baby is identical to that mother

You can make Animal Clones by using Embryo Transplants

• Sperm and egg cells are taken from the best. 
• Embryo that is developed splits many times to form clones.
• The cloned embryos can then be implanted into lots of animals where they will grown into babies. 
• They will be genetically identical.
• Hundreds of perfect offspring can be produced each year.

• Produces "perfect" offspring BUT "reduces gene pool" = new disease, will appear in every animal & species could be wiped out)

• Cloning could have to preserve endangered species

• Cloned animals may not be as healthy as normal ones > diseases

• There's a worry that humans may be cloned one day ... success follows many unsuccessful attempts

1. A useful gene is "cut" from organism's chromosome using enzymes 

2. Enzymes are then used to cut another organism's chromosome and then to insert into a useful gene.

3. This changes the DNA and all future genes artificially.

The same method can be used to transfer useful genes into animals and plants at the very early stages of their development. This means they will develop useful characteristics.

• Crops which have had their genes modified in this way are called genetically modified crops (GM crops).
• Examples of these include ones that are resistant to insect attacks or to herbicides.
• They generally show increased yields.

Cloning - produces exact copies

Genetic engineering - produces a unique set of genes  

                                          - genes copied within the same species genes can be                                                         swapped across species

Effects the populations of wild flowers and insects

Worried about people may develop allergies when they eat the crops 

Transplanted genes may escape into the natural environment 

Increase the yield, making more food 

They contain nutrients that humans are often missing 

Being grown elsewhere in the world without any problems 

More than 3 billion years ago, life on earth began as simple organisms from which all the more complex organisms evolved (rather than just popping into existence)

Similarities and differences between animals allows us to group them...

• Plants make their own food (by photosynthesis) and are fixed in the ground 
• Animals move about the place and can't make their own food 
• Microorganisms are different to plants and animals e.g. bacteria are single-celled 

1. Species with similar characteristics often have similar genes because they share a recent common ancestor, so they're closely related. They often look very alike and tend to live in similar types of habitat.

2. Sometimes, genetically different species may look alike too. But they're not closely related just adapted to live in the same habitat.

3. Evolutionary trees show common ancestors and relationships between organisms.  

1. If we see organisms in the same environment with similar characteristics, it suggests they might be in competition for food or shelter.

2. Differences between organisms in the same environment can show predator-prey relationships. 

Charles Darwin cam up the idea of natural selection...

V for variation - Members of the same species are not identical; every characteristic varies. 

C for competition - Limited resources of food in an environment; the animals and plants compete for food, water, shelter and space.

B for best adapted - Individuals with certain genes and characteristics make them more suited to the environment and will have a better chance of survival and then are more likely to breed.

P for pass on genes - The genes that are responsible fro the useful characteristics are more likely to be passed on to the next generation.

• Mutations are the change in an organisms DNA

• Usually they have no effect

• Occasionally can be useful by producing useful characteristics. This could give a better chance of survival and reproducing

• They can be passed on to further generations by natural selection

• The better mutations will accumulate in a population. 

1) He went against religious beliefs about how the earth was developed. 

2) Darwin couldn't give a good explanation for why these new useful characteristics appeared or exactly how individual organisms passed on their beneficial characteristics to their offspring. He didn't know about genes or mutations - discovered 50 years later.

3) There wasn't enough evidence to convince many scientists, because not many other studies had been done in this way. 

Lamarck (1744-1829)

Used a lot characteristics = more developed

Acquired characteristics = passed on

E.G.

Rabbit used his legs = longer legs 

Rabbits offspring = longer legs

Creationism - In which the Bible describes the creation of all species by God in 6 days. This does not allow for one species to gradually change or evolve into new species. The church did not believe in evolution. 

Lamarckism - It suggest that organisms receive characteristics that their parents develop during a lifetime. A stretched neck would be passed to baby giraffes who would inherit a longer neck. 

Darwinism - The theory of natural selection : V - C - B - P 

Hypothesis' are different because scientists have.. 

• Different beliefs (religion)

• Been influenced (religion)

• Think differently

 A theory is an accepted hypothesis

Independant - You change 

Dependant - You measure 

Control - You keep the same