Biology Foundation

Malnourishment    

A person is malnourished when they do not have a balanced diet

Lack of Nutrients

Metabolic Rate 

Chemical reactions in the cells of the body are carried out

the higher the muscle fat the higher the metabolic rate

a major set is RESPIRATION 

Inheritance  

we can inherit genes from our parents, this is an influence on our health and metabolic rate

cholesterol can be inherited from our parents, cholesterol is a substance that the body creates fat that we consume in our diet

Pathogens 

Microorganisms that cause infectious diseases are called pathogens

Bacteria 

Pathogenic bacteria reproduce rapidly inside the body and may produce poisonous toxins which make us feel ill.

e.g E.coli  produces toxins that cause fever symptoms when we have food poisoning

Viruses 

Viruses are much smaller than bacteria

all viruses are pathogens

they produce toxins and they damage the cells in which they reporudce, leading to illness

HIV 

HIV damages white blood cells, reducing immunity and leading to AIDS

Influenza virus releases toxins which cause aches and fever symptoms

The Immune System 

White blood cells defend our internal environment from pathogens

these form part of our immune system

cells that produce antitoxins that destroy toxins released by pathogens

cells that proudce antibodies that destroy specific pathogens

Preventing Transmission

In the 1850's semmelweiss recognised the importance of washing hands to prevent diseases spreading..this gradually reduced the number of deaths from infectious diseases in hospitals

Using drugs to treat disease 

Some medicines, including painkillers, help to relieve the symptoms of infectious disease, but do not kill pathogens

Antibiotics help to cure bacterial disease

by killing infective bacteria inside the body e.g penicillin

Antibiotics kill bacteria inside the body

Antibiotic Resistance

Pathogenic bacteria mutate, producing resistant strains

Antibiotics kill individual pathogens of the non-resistant strain

Antibiotics and vaccinations may no longer be effective against a new resistant strain

Epidemics and Pandemics

Epidemics- diseases that spread widely through one country

Pandemics- diseases that spread through several countries

e.g. Influenza

A viral disease, most people recover in a week. People who are old or very young or already ill can die.

Immunisation

Small pox was completely eradicated by the 1970s

You can be immunised by introudcing dead or inactive forms of the pathogen into the body

Growing Microorganisms 

Microorganisms are organisms that can only be viewed with a microscope

e.g bacteria, viruses and fungi

Culturing Microorganisms

They need to be provided with the conditions they eed to reproduce quickly:

nutrients, warmth and moisture

Bacteria can be grown in special media called agar;

this provides them with carbohydrate, protein and water

when agar is heated up it is liquid, it can be poured into a petri dish

In school and college laboratories should be incubated at maximum of 25 degrees

The Nervous System 

central nervous system-brain plus spinal cord

stimuli-changes in the environment

receptors-cells that detect stimuli

nerve impulse-electrical message that passes along a neurone

neurones-nerve cells

relay neurone-neurone in the central nervous system(CNS)

sensory neurone-never cell that transmits nerve impulse from a receptor to CNS

motor neurone-nerve cell that trainsmits nerve impulse from CNS to an effector

effector-a structure that the nervous system causes to respond-muscle or gland

Synapses

junctions between nerve cells.

when a nerve impulse arrives at the end of a neurone, chemicals are released

Receptors

receptors in the eye are sensitive to light

receptors in the ears are sensitive to sound

receptors in the ears are also sensitive to changes in position, and keep our balance

receptors on the tongue and nose are sensitive to chemicals;taste and smell

receptors in the skin that are sensitive to touch, pressure pant and temperature

Reflex Actions

reflex actions are automatic and rapid

they are simple responses that often protect the body from harm

they often involve sensory,relay and motor neurones

Hormones

Hormones are secreted by the glands

they control many processes within the body

Menstrual Cycle

the monthly release of an egg from a woman's ovaries

controlled by hormones and secreted by the pituitary gland and by the ovaries

Artificial fertility in controlling hormones

hormones can be synthesised artificially, they are very similar to human hormones

Oral Contraceptives

contain hormones to inhibit FSH production so that no eggs mature

may contain oestrogen and progesterone to inhibit egg maturation

Fertility Drugs

Can be given to women whose own level of FSH is too low to stimulate eggs to mature

contain FSH and LH

Stimulates eggs to mature and increases the chances of getting pregnant

Control In Plants

plants are sensitive to light,moisture and gravity:

their shoots grow towards light and against gravity

their roots grow towards moisture and in the direction of the force of gravity

plants produce hormones to coordinate and control growth

the auxin controls phototropism and gravitropism

the auxin diffuses away from the stimulus

it affects the growth of cells in different ways

in the shoots it causes increased cell growth, which causes the shoot to curve towards the stimulus

The uses of artificial plant hormones

plant growth hormones are used in agriculture and horticulture

agriculture is the large scale business involving cultivating of soil to proudce crops and raise livestock

horticulture is a small scale cultivation of fruits,vegetable and flowers

Weed Killers

Chemicals that are used that are specifix to the weeds e.g dandelions

they cause the weed to grow very quickly

the weed cannot sustain this rate of growth and dies.

Rooting Hormones

cuttings are taken from a plant, the cutting is dipped into rooting powders

Types of Drugs

Medical drugs: prescribed- a doctor must provide a prescription for these.

e.g antibiotics and strong painkillers such as morphine

non-prescribed-these can be bought in a chemist without a prescription

e.g pain killers such as aspirin and paracetmol

Recreational drugs: legal- e.g alcohol,caffeine,nicotine

illegal-ectsasy,cannabis,heroin

Drug Trials

Drugs are tested in series of stages to find out if they are safe and effective

new drugs are extensively tested for toxicity,efficacy and dose

Thalidomide

it is a drug that was developed as a sleeping pill, it was also found to relieve morning sickness in pregnant women

it has not been tested for this use, many babies born to mothers who took this pill have been found to suffer with severe limb abnormalities

Statins

a relatively new group of drugs used to lower blood cholesterol levels

a high level of cholesterol increases in a person's risk of having a heart attack or stroke

Drug Abuse

Some people use drugs recreationally, some of these drugs are more harmful than others.

Some of these drugs are legal such as alcohol and nicotine, some of these drugs are illegal such as ecstasy, cannabis and heroine

Addiction and Withdrawal

drugs can change the chemical processes in people's bodies, drugs work by affecting the synapses

some drugs make them work faster e.g caffeine, some make them work slower e.e cannabis

drug abusers become dependant or addicted to drugs, and may suffer withdrawl symptoms without them. Heroin and Cocaine are very addictive

Effects of drugs

Alcohol affects the nervous system by slowing down reactions

Nicotine is the addictive subsance in tobacco smoke

Tobacco smoke contains carcinogens, which are chemicals that cause cancer

Tobacco smoke also contains carbon monoxide which reduces the oxygen carrying capacity of the blood

Drugs in Sport

There are several types of drugs that an athlete can use to enhance their performance, some of these drugs are banned by the law.

Stimulants that boost bodily functions such as the heart rate, anabolic steroids which stimulate muscle growth

Survival

to survive, organisms require a supply of materials from their surroundings and other living organisms there.

organisms live, grow and reproduce in places where, and at times when, conditions are suitable.

Competition

animals often compete with eachother for: food, mates and territory

plants often compete with eachother for: light, water from soil, nutrients from soil

Adaptation

organisms have features which enable them to survive in the conditions they live in.

to make it more difficult for predators to catch them, to survive in conditions

Extreme Adaptations

extremophiles are organisms that live in extreme environments

some may be tolerant to high levels of salt, high temperatures or high pressures

Extreme Animals

animals may be adapted for survival in dry and arctic environments by means of:

changes to the surface area, thickness of insulating coat, amount of body fat,camouflage

e.g Camel:

the camel can go without food or water for 3 to 4days

fat stored in their humps provides long term food reserve and a supply of water

they are tall and thin, increasing heat loss by radiation

Polar Bear: has thick fur and fat beneath its skin to insulate it. Their large furry feet help to distribute their weight as they walk on slow and ice.

Extreme Plants

plants may be adapted to survive in dry environments by means of changes to the surface area, water storage tissues and extensive root systems

Leaves are spines, spines guard against most browsing herbivorous animals

Microorganisms

Microorganisms have adaptations that enable them to survive in different environments

some bacteria can survive extreme conditions- temperatures as little as -15 to as high as 121 degrees, ph values 0.0-12.8

Environmental Change

changes in the enviroment affect the distribution of living organisms

non living factors: light, oxygen, water, temperature

living factorsL: food, predation, grazing, disease, competition

Energy Transfer

radiation from the sun is the source of energy for most communities of living organisms. Green plants and algae capture a small part of the solar energy which reaches them.

Food Chain- diagram to represent feeding relationships between organisms

Pyramids of biomass- the biomass at each stage can be drwn to scale and shown as a pyramid of biomass. Biomass-mass of living material

Recycling in Ecosystems

living things remove materials from the environment for growth and other processes.

these materials are returned to the environment either in waste materials or when living things die and decay.

Materials decay because they are broken down(digested) by microorganisms(decomposers). Microorganisms digest materials faster in warm, moist conditions

Carbon dioxide is removed from the environment by green plants and algae for photosynthesis.

The carbon from the carbon dioxide is used to make carbohydrates, fats and proteins which make up the body of plants and algae.

Some of the carbon dioxide is returned to the atmosphere when green plants and algae respire

Genetic Material

a cell is the basic unit life, all organisms are made up of cells

the nucleus is a large organelle found in all cells, that contains the genetic information.

Chromosomes are thread-like structures made of DNA found in the nucleus

Genes are small sections of a chromosome that control the characteristics of an organism.

these are passed on from parent to offspring, resulting in offspring of plants and animals having similar characteristics to their parents. Eg hair colour and petal colour

different genes control the development of different characteristics of an organism.

Sexual Reproduction

involves two parents, they produce male and female sex cells (gametes)

in humans these are sperm and eggs, fetilisation offcurs-joinig of male and female gametes.

Asexual Reproduction

involves only one individual as a parent, there is no fusion of gametes.

there is no mixing of genetic information and so no variation in the offspring.

These genetically identical individuals are known as clones.

The causes of variation

differences in the characteristics of different individuals of the same kind may be due to differences in. The genes they have inherited.

Genetic Factors

sexual reproduction-leads to genetic variety in the offspring.

asexual reproduction-no genetic variation in the offspring

Environmental Factors

nutrition, temperature, light, physical forces

Cloning

humans can carry out various procedures to create clones of plants and animals.

These new individuals are genetially identical to the parents. New plants can be produced quickly and cheaply by taking cuttings from older plants.

Tissue Culture

this uses small groups of cells from part of a plant to grow new plants

Embryo Transplants

this involves splitting apart from cells from a developing animal embryo before they become specialised. The identical embryos are then implanted into the wombs.

advantages:this technique could be used to make many copies of cows that have a high milk yield.

concerns:people do not want this procedure to be used in humans. It could be used to provide more embryos for scientific testing.

Adult Cell Cloning

the nucleus is remove from an unfertilized egg cell. this is replaces with the nucleus of an adult cell. an electric shock is used to start the cell dividing to form embryo cells

advantages: this could be used to clone animals with desired characteristics. concerns:people do not want human babies to be cloned.

Darwin

darwin's theory of evolution by natural selection states that all species of living things have evolved from simple life forms that first developed more than three billion years ago.

These first organisms were very simple single-celled organisms, similar to bacteria.

the theory of evolution by natural selection was only accepted because:

the theory challened the idea that god made all the animals and plants that live on earth. There was insufficient evidence at the time that the theory was published to convince many scientists. The mechanism of inheritance and variatio was not known until 50years after the theory was published.

Conflicting theories on evolution

scientists may produce different hypothesis to explain similar observations, before darwin, lamarck used a different theory.

Classification

studying the similarities and differences between organisms allows us to classify living organisms into animals, plants and microorganisms. Models allow us to suggest relationships between organisms. Evolutionary trees are used to represent the relationships between organisms.

Darwin's theory of natural selection

organisms produce large numbers of offspring, individual organisms within a particular species may show a wide range of variation because of differences in their genes.

Mutations

errors occur when the DNA is replicated prior to cell division. Errors may occur when chromosomes are separated during cell divison. Genes control the synthesis of proteins,therefore a change in a gene or a new sequence of genes can result in different proteins being synthesised.