Biology: B1

The whole topic

Diet and Exercise

• Healthy diet = Balanced Diet• Exercise increases the amount of energy used

by the body and decreases the amount of stored fat

• Inherited factors can affect your metabolic rate and your blood cholesterol levels.

Pathogens

• Bacteria are 100 times smaller than body cells, and they reproduce quickly

• Some Bacteria can damage your cells or produce toxins

• Virus’ are 100 times smaller than bacteria • They invade the body cells and replicate inside the

cell until the cell bursts.

White Blood Cells

White blood cells travel in the blood. If they come across an invading microbe they act in theses ways :

• Engulf these microbes and digest them

• Produce antibodies

• Produce antitoxins

Engulfing and Digesting

Producing Antibodies

• Every pathogen has an antigen on its surface, when white blood cells come across one they don’t know they start producing proteins to kill them. These are called antibodies

White blood cell It produces an New microbes attacked detects microbe antibodies by new antibodies

Producing antitoxins

• These are produced by the white blood cells to counteract the toxins made by the invading bacteria

VaccinationPros ConsHelp control infectious diseases, to stop death in that country

Vaccines don’t always work, so they wouldn’t give immunity

Epidemics are less likely to spread even if only a percentage of the population is vaccinated

People can have reactions to the vaccines such as swelling or even seizures. However these are uncommon

Sense organs

• Sense organs detect stimuli • They all contains different receptors i.e eyes

have light receptors. This means it is sensitive to light

• They are: eyes; nose; ears; mouth; tongue and skin

CNS

• The central nervous system is where the information from the sense organs is sent, so reflexes and actions can be coordinated.

• It consists of the brain , spine and the neurone path way

Neurones

Sensory- nerve cells that carry electrical signals from the receptors to the CNS

Relay- nerve cells that carry electrical signals from the sensory neurons to the motor neurons

Motor- nerve cells that carry electrical signals from the CNS to the effecter muscle/gland

Receptor CNS CNS Effecter

Sensory Relay Motor

Hormones and Nerves

Nerves Hormones

Very FAST SLOWER action

Act for a SHORT time Act for a LONG time

Act in a PRECISE area Act in a GENERAL way

Menstrual Cycle

STAGE 1: This is the break down of the uterus lining

STAGE 2: The lining of the uterus builds up

STAGE 3: An egg is released on day 14. These are the most fertile days

STAGE 4: The wall is maintained for these days. If no fertilised egg implants then the cycle starts again

Hormones

FSH- Produced by the pituitary gland - Causes eggs to mature in the ovaries - Stimulates the ovaries to produce oestrogen

Oestrogen- Produced in the ovaries - Causes pituitary to produce LH - Inhibits the release of FSH

LH- Produced in the pituitary gland - Stimulates the release of an egg at the middle of the

menstrual cycle

Plant Hormones

• Auxin is plant hormone that controls growth near the tips of the shoots and the roots

• Phototropic, Hydrotropic, or Geotropic• If auxin move backwards it will stimulate cell

elongation • If the tip is removed, no auxin is available so

may stop growing

Shoots reaction to stimuli

Gravity Gravity

Testing medicines

1. Drug tested on human cells/tissues2. Drug tested on live animals3. Healthy human volunteers (small)4. People suffering (includes placebo)5. Ongoing reporting from doctors

Recreational Drugs

• Hard drugs- are seriously addictive and normally more harmful

• People use them for stress relief, enjoyment, peer pressure or relaxation

• Tobacco and Alcohol are both legal but they both can cause serious damage to your body

Second Part

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Adaptations

Cold places • Small surface area compared to volume• Well insulated (blubber• Hairy coats and/or greasy fur

Adaptations

Hot places• Large surface area compared to volume• Excellent water storage tissues• Good absorbers of water

Adaptations

Other• An armour

• Poisons

• Warning colours ( i.e wasps are bright yellow)

Competition For survival

• Plants: light, space, water and minerals

• Animals: space(territory), food, water and mates

Changes Causes by different factors

• Living things: Occurrence of diseases Number of predators Availability of food Number of competitors• Non- Living: Average Temp Average Rainfall Air/Water pollution

Population Increasesbecause of more food, this means they will survive for longer = more children

Population Decreasesbecause there is less food, or more disease or more pesticides. This means they will die = less children

Indicators They measure environmental change

• Lichen- show levels of air pollution• Mayfly (or other invertebre that need oxygenated

water) – they show levels of water pollution• Rat-tailed maggots and sludgeworms – indicate high

level of water pollution• Satellites- measure temp of the sea surface and

levels of snow fall• Rain gauges- measure rainfall• Automatic Weather Station- atmospheric temps

Pyramids of Biomass

• 100 flowers 10 rabbits 1 fox 500 fleas

• 15kg 10kg 6kg 1kg

Flowers

Rabbits

Fox

Fleas

Decay and Decomposers

• Plants take in carbon, oxygen, hydrogen and nitrogen. They turn these elements into complex compounds which they pass on through the food chain

• Microorganism work best in warm, moist conditions.

• The decomposers secrete enzymes to break down the products

Carbon Cycle shows how carbon is recycled

CO2 in the air

Fossil Fuels

Carbon compounds being decayed by microorganisms

Burn

ing

Burn

ing

Photosynthesis

Variation

• Caused when two gametes meet and fuse. The offspring will have a mix of the two DNA’s causing Variation

• The environment can also cause variation, the exposure to the sun causes a lot of variation

• Most characteristics are determined by the mix of genetic and environmental variation

Genes, Chromosomes and DNA

Most cells have a nucleus. This contains genetic information.

A human cell has 23 pairs of chromosomes

Chromosomes carry genes. These control development of different characteristics

GENE- This is a long strand of DNA

Different versions of the same gene give different characteristics

Sexual Reproduction

• Two organisms (father and mother) that have different genetic information

• Parents produce gametes• In humans a gamete has 23 chromosomes (half the

normal number)

• The gametes then fuse together, so the offspring then has the normal number of chromosomes

• The offspring has mixture of characteristics from mother and father• This produces Variation

Asexual Reproduction

• An ordinary cell divides in two, this is a clone because it has the same genetic information

Cloning Cuttings

Cloning Embryo transplants

1) Sperm and eggs cells are taken from a prize winning bull and cow2) Embryo splits, divides and develops3) These are implanted into surrogate cows

4) All offspring will be genetically identical

Adult cell cloning

Nucleus removed

Cell removed

Electric shock

Implanted into a surrogate mother.

Live animal

Issues of cloning

• There is reduced gene pool so one disease could wipe out the population

• Animals might be less healthy because of the cloning

• Worry about human cloning and the implicationsHowever• Could lead to greater understanding of development

of embryos, ageing and age-related disorders• Preserve endangered species

Genetic engineering

Example of using enzymes to ‘cut and paste’ genes

A useful gene is cut out of a chromosome using enzymes. This is put in to a bacteria. This then reproduced. This is how they make insulin

GM Crops

• Increase the yield of crops• Crops made for people to add nutrients where

they are lacking• Grown elsewhere without any problem• Reduce biodiversity • Some weeds could become resistant and

create a ‘superweed’ variety

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