Edexcel GCSE Biology 2BIO1 - Unit B1 Topic 2

Class notes for the 2011 Edexcel GCSE

Biology Unit B1 Topic 2 - Responses to a changing environment

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  • Created on: 12-01-12 10:31
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Biology B1 Topic 2
B1 Topic 1
Homeostasis
Biology Topic 2 Plant Hormones
Nervous system
Topic 3
B2
Science B3
Chemistry
Physics
Homeostasis - the body's ability to maintain a stable internal environment
Thermoregulation - control of body temperature
Osmoregulation - control of water
Blood Glucose regulation - control of glucose levels in the body
Vasodilation - widening of blood vessels
Vasoconstriction - narrowing of blood vessels
Endocrine gland - area of the body that produces a specific hormone
Diabetes - Disease that affects levels of insulin within the body
1

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Biology B1 Topic 2
Homeostasis
Homeostasis is the maintainance of a constant
internal environment in response to a changing
external environment.
Hormones have an important role in this system
they are released by glands, in to the blood
stream, where they reach target cells. A specific
hormone will fit a specific receptor protein, and
this brings about a change in that cell.…read more

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Biology B1 Topic 2
Homeostasis is.....
It is important because....…read more

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Biology B1 Topic 2
Negative Feedback
Negative feedback is the mechanism by which the body
maintains conditions within particular limits. The body
will do this by opposing a change that deviates from the
normal.
Thermoregulation
Human life is only compatible with a narrow range of
temperatures. Core temperature changes within 3°C will
not interfere with physiological functions, but any
variation outside that range has very serious effects.…read more

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Biology B1 Topic 2
Thermoregulation
Temperature in mammals is detected by
thermoreceptors in the skin and hypothalymus which
is in the brain.
Changes in temperature bring about nerve impulses
from the brain to the muscles and glands which will
bring about changes depending on whether it is hot or
cold.…read more

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Biology B1 Topic 2
Complete the diagrams to explain the responses to
change in temperature
Why is thermoregulation so important?
Surface Area to Volume Ratio
Small objects have a
much larger sa:vol
ratio and therefore
loose heat much
faster than larger
objects
6…read more

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Biology B1 Topic 2
Hyperthermia--Overheating of the body caused only by an
external factor, as for example a hot environment, or a hot
bath.
Hypothermia--A low body temperature, as caused by
exposure to cold weather or a state of low temperature of
the body induced by decreased metabolism.
Thermoregulation Worksheet
Osmoregulation
Water is very important to us. You can survive weeks
without food, but only days without water
If blood becomes too concentrated because water is
removed, then the cells become dehydrated.…read more

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Biology B1 Topic 2
Osmoregulation
Complete the table showing the steps for osmoregulation
8…read more

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Biology B1 Topic 2
Blood Glucose Control
Certain tissues like the brain and retina are very sensitive to
changes in glucose levels. An excess or deficit of blood glucose
for more than a few hours can result in the loss of consciousness
and brain damage.
The level of glucose in the blood is normally controlled by two
hormones. These are called insulin and glucagon. Both of these
are produced in the pancreas
Insulin and glucagon work in opposition to one another.…read more

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Biology B1 Topic 2
Blood Glucose levels change
throughout the day
Plot this data in a graph
Explain the pattern it shows using
information about the blood
glucose control mechanism
include negative feedback loops
Test the urine samples using clinistix
What do you notice?
Can you explain the results?
negative
low glucose
medium glucose
high glucose
10…read more

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