Diet and Exercise
A person is malnourished when they do not have a balanced diet
Lack of Nutrients
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
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
Microorganisms that cause infectious diseases are called pathogens
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 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 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
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
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
A viral disease, most people recover in a week. People who are old or very young or already ill can die.
Small pox was completely eradicated by the 1970s
You can be immunised by introudcing dead or inactive forms of the pathogen into the body
Microorganisms are organisms that can only be viewed with a microscope
e.g bacteria, viruses and fungi
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
Nerves and Hormones
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
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
Nerves and Hormones.2
junctions between nerve cells.
when a nerve impulse arrives at the end of a neurone, chemicals are released
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
Nerves and Hormones.3
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 are secreted by the glands
they control many processes within the body
the monthly release of an egg from a woman's ovaries
controlled by hormones and secreted by the pituitary gland and by the ovaries
Nerves and Hormones.4
Artificial fertility in controlling hormones
hormones can be synthesised artificially, they are very similar to human hormones
contain hormones to inhibit FSH production so that no eggs mature
may contain oestrogen and progesterone to inhibit egg maturation
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
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
Control In Plants.2
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
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.
cuttings are taken from a plant, the cutting is dipped into rooting powders
The Use and Abuse of Drugs
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
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
Use and Abuse of Drugs.2
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
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
The Use and Abuse of Drugs.3
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
The Use and Abuse of Drugs.4
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
Interdependence and Adaptation
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.
animals often compete with eachother for: food, mates and territory
plants often compete with eachother for: light, water from soil, nutrients from soil
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
Interdependence and Adaptation.2
extremophiles are organisms that live in extreme environments
some may be tolerant to high levels of salt, high temperatures or high pressures
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
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
Interdependence and Adaptation.3
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.
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 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
Interdependence and Adaptation
changes in the enviroment affect the distribution of living organisms
non living factors: light, oxygen, water, temperature
living factorsL: food, predation, grazing, disease, competition
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
Waste Materials from Plants and Animals
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 Variation and its Control
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.
Genetic Variation and its Control.2
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.
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 Variation and its Control.3
sexual reproduction-leads to genetic variety in the offspring.
asexual reproduction-no genetic variation in the offspring
nutrition, temperature, light, physical forces
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.
this uses small groups of cells from part of a plant to grow new plants
Genetic Variation and its Control.4
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'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.
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.
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.