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Biology B4- Homeostasis

Keeping a steady state:

Automatic control systems in the body keep factors steady, including body temperature and
water level.
Artificial control systems are similar to body control systems; they both have receptors, a
processing centre and also effectors.
Strenuous (tiring) exercises and extreme climates can affect homeostasis.…

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The brain processes information about temperature control in the hypothalamus, and
effectors (sweat glands and muscles) produce responses to keep the body temperature
steady.
Vasodilatation and vasoconstriction control the amount of blood flowing near the skin
surface.
Vasodilatation widens the blood vessels and Vasoconstriction narrows the blood vessels.
Hypothermia: causes:…

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B5- Growth and Development

The cell cycle

Cells go through cycles of growth and divisions:
I. During cell growth the number of organelles increases, and chromosomes are
copied.
II. During cell division copies of the chromosomes separate, and then the cells divide.
Cell division by mitosis produces two new cells…

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Meristem cells can re-grow whole parts of the plant, which means that gardeners can make
new plants from cuttings.
Plant hormones (auxins) affect how plant cells develop.
Plants grow towards the light; this response is called phototropism.
Auxin builds up in cells on a shoot's shady side, which make the…

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B6- Brain and Mind

A mammal's nervous system

The nervous system is made up of the central nervous system (CNS) and peripheral nervous
system.
The CNS coordinates an animal's response via sensory and motor neurons.
Receptors and effectors can be single cells or parts of complex organs.

Nerve Impulses

The…

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This is the end of B4, B5 and B6 summary. I hope it's helped. Thank you & Good luck in the exam.

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