New spec, B1 notes, AQA

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  • Created on: 14-11-12 18:33
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Biology GCSE Revision
We look like our parents because of the information carried by
GENES. Gamete is a sex cell which has half the chromosome
number of ordinary cells.
The genetic information is carried in the nucleus in your cells. In the
nucleus are all the plans for making a new cell.
Inside the nucleus are all of your cells that look like a thread called
CHROMOSOMES. Chromosomes are made up of a special chemical
called DNA.
Humans have 46 chromosomes. We have 23 pairs of chromosomes
in all of our body cells.
Genes control what an organism is like.
There are 2 types of reproduction, and they are:
Asexual reproduction
Sexual reproduction
ASEXUAL REPRODUCTION involves 1 parent. This type of
reproduction gives rise to identical offspring known as CLONES.
SEXUAL REPRODUCTION involves 2 parents, a males sex cell and a
female sex cell. These sex cells (gametes) join together to form an

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Gardeners often produce new plants by taking their cuttings from
older plants. To take a cutting you:
1. Remove a small piece of a plants e.g. stem or leaf
2. Plant it, keeping it in the right conditions, new root and
shoots shall eventually form.
This method is quick and cheap. The cutting will be genetically
identical to the parent's plants.
Today we use hormone rooting powders to encourage cuttings to
grow.…read more

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How to clone animals?
1. Divide each embryo into several individual cells
2. Each cell grows into an identical embryo
3. Transfer embryos into their host mothers, which have been
given hormones to get them ready for pregnancy
4. Identical cloned claves are born. They are not biologically
related to their mothers.
Cloning cattle embryos and transferring them to host cattle is skilled
and expensive work.…read more

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GENETIC ENGINEERING involves changing the genetic material of an
organism. You take a gene from one organism and transfer it to the
genetic material of a completely different organism.
There is a limit to the types of proteins that bacteria are capable of
making. Scientists have found that genes from one organism can be
transferred to the cells of another type of animal or plant. At it
developed it forms new characteristics.
There are many benefits of genetic engineering.…read more

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Golden rice helps them to get a enough amount
of vitamin A.
You're NERVOUS SYSTEM helps you to know what is going on in the
world around you. It enable to you to react to your surroundings
and coordinate your behaviour.
Your nervous system carries electrical signals which are called
IMPULSES. They travel fast from 1 to 120 metres per second. This
means you can react to changes in your surroundings very quickly.
Any changes around you are known as STIMULI.…read more

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When a sensory receptor finds a stimulus, the information goes
through special cells called NEURONS. They are found in hundreds
or thousands of neurons also known as NERVES.
The impulse travels along the neuron until it reaches the CENTRAL
NERVOUS SYSTEM OR CNS. The CNS is made up of the brain and
the spinal cord.…read more

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Hormones stimulate the ovaries to produce the female sex
hormone oestrogen
FSH ­ stored in the pituitary gland. It makes eggs mature in
the ovaries. FSH also makes the ovaries to produce oestrogen.
OESTROGEN- stored and made in the ovaries. It stimulates the
lining of the womb to build up ready for pregnancy. It slows
down the production of FSH
LH ­ made in the pituitary gland. It causes the eff to be
released.…read more

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Our body temperature is 37 degrees. ENZYMES work best when
controlling your body. Out body controls our temperature many
ways such as sweating can make you cool down and shivering can
warm you up.
They NERVOUS SYSTEM is very important, it responds to changes in
the environment.
Your body cannot work properly is your INTERNAL ENVIROMENT
keeps changing.…read more

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Some women want children but simply do not make enough FSH
so no eggs mature in the overies
ARTIFICAL FSH stimulated the egg in the ovary to mature
Light/ temperature change ­ shoots grow upward towards
Water (moisture)
Gravity (roots growing downwards)
AUXINS are plant hormones which control the rate and direction of
growth of roots and shoots. This is known as PLANT TROPISM
Plants contain GROWTH HORMONES at the tips of the roots and
shoots.…read more

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Plants are sensitive to light. This is called PHOTOTROPISM.
They are also sensitive to gravity (GEOTROPISM) AND MOISTURE.
These responses are coordinated by hormones called Auxins.…read more


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