Biology Unit 1

The new syllabus for the Biology GCSE Unit 1

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  • Created by: Ailis
  • Created on: 09-06-12 14:42

Keeping Healthy - Diet + Exercise

To stay healthy you need - BALANCE DIET + REGULAR EXERCISE



There are four main food groups:

  • Carbohydrates- potatoes, pasta, bread - source of energy
  • Fats- cheese, butter, margerine- source of energy, makes cell membranes, insulates
  • Proteins- meats, fish, eggs -growth and repair
  • Vitamins + Minerals - fruit and veg - healthy functioning of the body
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Keeping Healthy - Diet + Exercise 2

Respiration - a chemical reaction that allows cells to release energy from food.

Metabolic Rate - speed at which such chemical reactions take place in the body and varies because of several factors, including age, gender and inherited factors.

Metabolic Rate also affected by- 

  • proportion of muscle to fat in the body
  • amount of exercise and other physical activity

The metabolic rate increases and stays high for a while after. People who do regular exercise are healthier than those who don't.

There are other factors aswell such as inherited factors.

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Keeping Healthy - Defending Against Infection

Pathogens:Bacteria are living cells. Can multiply rapidly in favourable conditions. Once inside the body they release toxins and poisons which make us feel ill.

Diseases caused by Bacteria:

  • food poisening
  • cholera
  • typhoid
  • whooping cough

White blood cells injest the pathogens by releasing antibodies which destroy the infectious microoganisms and antitoxins which neutralise toxins.

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Keeping Healthy- Defending Against Infection 2

Pathogens:Viruses are many times smaller than bacteria. They can only reproduce when inside a host cell and they damage the cell by doing this. Once inside they make copies of themselves and eventually the copies burst he cell open making the virus spread around the body.

Diseases caused by viruses:

  • flu + colds
  • measles
  • mumps
  • rubella
  • chicken pox
  • AIDs
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Keeping Healthy- Defending against infection 3

White Blood Cells:

  • ingest pathogens and destroy them
  • produce antibodies to destroy particular pathogens
  • produce antitoxins which counteract the toxins released by pathogens
  • the pathogens are not the disease - they cause the disease
  • white blood cells do not eat the pathogens - they ingest them
  • antibodies and antitoxins are not living things - they are specialised proteins.
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Keeping Healthy- Defending Against Infection 4


Antibodies are proteins. They can neutralise pathogens in a number of ways. For example, they can:

  • bind to pathogens and damage or destroy them
  • coat pathogens, clumping them together so that they are easily ingested by white blood cells called phagocytes.

Vaccines can contain:

  • live pathogens treated to make them harmless
  • harmless fragments of the pathogen
  • dead pathogens.
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Nerves + Hormones - The Nervous System

Receptors- Specialised cells that detect changes in the environment called Stimuli.

Cells- Most animal cells have a nucleus, cytoplasm and cell membrane. Light receptors have these cell components too.

The human central nervous system (CNS) consists of the brain and spinal cord. When a receptor is stimulated it sends a signal along the nerve cells, also called neurones, to the brain. The brain then coordinates the response.

Neurones are nerve cells. There are three different types, all with a different function:

  • sensory neurones carry signals from receptors to the spinal cord and brain
  • relay neurones carry messages from one part of the CNS to another
  • motor neurones carry signals from the CNS to effectors
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Nerves And Hormones - Reflex Actions

In a simple reflex action:

stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector

An effector is any part of the body that produces the response. Here are some examples of effectors:

  • a muscle contracting
  • a gland releasing (secreting) a hormone or other chemical.
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Nerves + Hormones - Control in the body

Hormones are chemicals secreted by different glands, for example:

Pituitary Gland- releases LH + FSH used in the women's menstrual cycle.

Andrenal Gland- releases adrenaline

Ovaries- releases oestrogen

Pancreas- releases insulin

Testes - releases testosterone

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Nerves And Hormones - Control in the body

The uses of FSH + LH


  •  it stops FSH being produced - so that only one egg matures in a cycle
  •  stimulates the pituitary gland to release luteinizing hormone (LH), which triggers ovulation (the release of the mature egg from the ovary).


  • it causes an egg to mature in an ovary
  • it stimulates the ovaries to release the hormone oestrogen.
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Nerves And Hormones - Control in the body

Oral Contraceptives- contain oestrogen and progesterone. They stop FSH meaning they stop the maturing of eggs in the ovaries.

Benefits and risks

Oral contraceptives allow couples to choose the time they start a family, and choose the time they stop having children.

The first birth-control pills contained higher amounts of oestrogen than the pills taken today. This caused women to have significant side effects, such as changes in weight, mood and blood pressure. Modern birth-control pills contain much less oestrogen. Some only contain progesterone, which also leads to fewer side effects.

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Nerves And Hormones- Control In The Body

Fertility Treatments

There are many different fertility treatments, most of which contain FSH and LH.

IVF- This is where the egg is fertilised outside the woman’s body and then implanted back into her uterus. As FSH can also be used to encourage the production of several mature eggs at once, it is used as part of IVF to increase the number of eggs available for fertilisation.

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Nerves And Hormones- Control In Plants

Plants need light and water for photosynthesis. Plant responses - called tropisms - help make sure that any growth is towards sources of light and water.

There are two main types of tropism:

  • positivetropism – the plant grows towards the stimulus
  • negative tropism– the plant grows away from the stimulus.

Auxins are a family of hormones found in plants. Auxins are mostly made in the tips of the shoots and roots, and can diffuse to other parts of the shoots or roots. They change the rate of elongation in plant cells, controlling how long they become. Shoots and roots respond differently to high concentrations of auxins:

  • cells in shoots grow more
  • cells in roots grow less.
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 Environment :all the conditions that surround a living organism

Habitat: the place where an organism lives

Population: all the members of a single species that live in a habitat

Communityall the populations of different organisms that live together in a habitat

Ecosystem a community and its habitat

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Extremophiles are organisms that live in very extreme environments and can survive conditions that would kill most other organisms. The extreme conditions can include:

  • high temperatures
  • high concentrations of salt in water
  • high pressures.
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Environmental Change

Lichens are plants that grow in exposed places such as rocks or tree bark. Rainwater contains just enough nutrients to keep them alive. Air pollutants dissolved in rainwater, especially sulfur dioxide, can damage lichens, and prevent them from growing. This makes lichens natural indicators of air pollution. For example:

  • bushy lichens need really clean air
  • leafy lichens can survive a small amount of air pollution
  • crusty lichens can survive in more polluted air.

level of water pollutionindicator species clean mayfly larva low freshwater shrimp high water louse very high rat-tailed maggot, sludgeworm

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Food Chains + Energy in Biomass

producers green plants and algae

they make food by photosynthesis

primary consumers usually eat plant material - they are herbivores

for example rabbits, caterpillars, cows and sheep

secondary consumers usually eat animal material - they are carnivores

for example cats, dogs and lions

predators kill for food

they are either secondary or tertiary consumers

prey the animals that predators feed on scavengers feed on dead animals

for example, crows, vultures and hyenas are scavengers

decomposers feed on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces

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The Carbon Cycle

The factors that affect the rate of decay include:

  • moisture
  • temperature
  • amount of available oxygen.

Removing carbon dioxide from the atmosphere

Green plants and algae remove carbon dioxide from the atmosphere byphotosynthesis. The carbon becomes part of complex molecules such as proteins, fats and carbohydrates in the plants and algae.

Returning carbon dioxide to the atmosphere

Organisms return carbon dioxide to the atmosphere by respiration. It is not just animals that respire. Plants, algae and microorganisms do too.

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Chromosomes, found in the cell nucleus, contain many genes. A gene is a section of DNA, which carries coding for a particular protein. Different genes control the development of different characteristics of an organism. Many genes are needed to carry all the genetic information for a whole organism.

Inherited variation

Variation due to genetic causes is inherited variation. For example, children usually look a little like their father, and a little like their mother, but they will not be identical to either of their parents. This is because they get half of their inherited features from each parent.

Here are some examples of inherited variation in humans:

  • eye colour
  • hair colour
  • skin colour.
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Characteristics of animal and plant species can be affected by factors such as:

  • climate
  • diet
  • accidents
  • culture
  • lifestyle.

Variation caused by the conditions is called environmental variation. Here are some other examples of features that show environmental variation:

  • your language
  • your religion
  • flower colour in hydrangeas (as these plants produce blue flowers in acidic soil and pink flowers in alkaline soil).
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the female egg and the male sperm fuse to create a zygote cell which then turns into an embryo. 23 chromosomes from the male and female each make 46 chromosomes in 23 pairs ( reproduction happens when a male gamete and a female gamete join.This fusion of gametes is called fertilisation. Sexual reproduction leads to variety in the offspring. Animals and plants can reproduce using sexual reproduction.

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Asexual Reproduction

Asexual reproduction only needs one parent, unlike sexual reproduction, which needs two parents. Since there is only one parent, there is no fusion of gametes and no mixing of genetic information. As a result, the offspring are genetically identical to the parent and to each other: in other words, they are clones.

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Adult Cell Cloning

Adult cell cloning involves several steps:

  1. the nucleus is removed from an unfertilised egg cell and discarded
  2. the nucleus is removed from an adult body cell and injected into the egg cell
  3. an electric shock is applied to make the egg cell begin to divide to form an embryo
  4. while it is still a ball of cells, the embryo is inserted into the womb of an adult female
  5. the embryo continues to grow and develop
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Genetic Modification

Certain enzymes can cut pieces of DNA from one organism, and join them into a gap in the DNA of another organism. This means that the new organism with the inserted genes has the genetic information for one or more new characteristics. 

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Darwin- survival of the fittest, adaptation

  • Darwin’s theory conflicted with religious views that God had made all the animals and plants on Earth
  • Darwin did not have enough evidence at the time to convince many scientists
  • it took 50 years after Darwin’s theory was published to discover how inheritance and variation worked.


  1. A characteristic which is used more and more by an organism becomes bigger and stronger, and one that is not used eventually disappears
  2. Any feature of an organism that is improved through use is passed to its offspring.
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Natural Selection

The theory of evolution states that evolution happens by natural selection. The key points are that:

  • individuals in a species show a wide range of variation
  • this variation is because of differences in their genes
  • individuals with characteristics most suited to the environment are more likely to survive and reproduce
  • the genes that allow these individuals to be successful are passed to their offspring.
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Words To Remember!


  • Variation
  • Adaptation
  • Survive
  • Reproduce


  • Mutate
  • Resist
  • Survive
  • Asexually Reproduce
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charlotte wilson


Hi, does this include everything in unit 1? thanks, x

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