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2. The Earth in the Universe
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5.3.
The importance of the Earth’s movements
for living things
The movements of the Earth cause days and nights and also the seasons. We
have seen that the number of hours of daylight (day) and darkness
8
(night) vary
depending on the season and the hemisphere we are in. In addition to these
variations, there are also changes in the average temperature in an area during
the year.
Living things can detect these variations. They influence their behaviour and cause
them to
adapt
to their environment.
These are some examples of adaptation:
Key concepts
❚
The Earth takes 365 days,
5 hours and 49 minutes to
complete one revolution of
the Sun.
❚
The Earth’s revolution and
the tilt of the Earth’s axis
cause the seasons.
❚
The Earth takes 23 hours
and 56 minutes to complete
one rotation on its axis.
❚
The Earth’s rotation causes
day and night.
Many trees
lose their leaves
in autumn,
when they detect a decrease in the hours
of daylight. In the same way they
sprout
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new leaves
in spring, with the increase
in the hours of daylight.
Understand
28.
Listen and say true or false. Correct the false sentences.
Flowering and forming of fruits
also
depend on temperatures and hours of
daylight and darkness.
Not all plants flower and form fruit in the
same season.
Animals are also sensitive to the
consequences of the Earth’s movements.
For example, the
mating and breeding
seasons
of many animals start when the
days get shorter and temperatures lower.
In this way, the babies will be born during
the ideal season for feeding them.
Another example of adaptation is
migration
. Some birds migrate at certain
times of the year.
For example, the majority of the white
storks, populations spend the winter
in sub-Saharan Africa, and migrate to
Europe for the summer.
7
8
darkness
:
state of being dark,
without any light
9
sprout
:
start to grow
