[Stems – leaves – roots]

3- The stems of desert plants are mostly -------------

[Short and weak – strong and tall – short and strong]

4- The stem of Elodea plant is --------------- [strong – elastic – both]

5- -------------- is an example of animals that undergo hibernation.

[Desert snail – jerboa – frog – all the previous]

6- Water is stored in the leaves of ------------------ plant.

[Elodea – cactus – calamagrostis – opuntia]

7- Leaves are reduced into spines in the ------------------- plant.

[opuntia – cactus – wheat – Elodea]

8- Camel stores the food in its hump in a form of -------------------

[Proteins – fats – water]

Q.4: Compare between Elodea plant and calamagrosits plant from:

Point of comparison	Elodea	calamagrosits
The environment	--------------------	--------------------
Roots	--------------------	--------------------
Leaves	--------------------	--------------------
Stem	--------------------	--------------------

Q.5: Mention an example that clarifies:

1- Camouflage: --------------------------------------------------------------------------

2- Hibernation: --------------------------------------------------------------------------

3- Aestivation: ---------------------------------------------------------------------------

Q.6: What happen in the following cases:

1- Absence of air chambers in the elodea plant's stem.

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2- The disability of some living organism to adapt with the environment.

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