Chapter 7: Adaptations of Plants in Different Habitats

Question 1

What is meant by adaptation?

Answer 1

• adjustment of an organism to the environment

Question 2

What are the 4 classifications of plants based on habitats?

Answer 2

• mesophytes
• halophytes
• hydrophytes
• xerophytes

Question 3

What are halophytes and mesophytes?

Answer 3

Halophytes
- plants that live in swampy habitats at the river mouth
- area is rich in salt content ( high salinity )
- Ex: mangrove tree
Mesophytes
- not too dry nor wet with an adequate supply of water
- most plants are mesophytes
- Ex: Hibiscus plants, mango tree and rubber tree

Question 4

What are hydrophytes and xerophytes?

Answer 4

Hydrophytes
- plants that live in aquatic habitats either on the water surface or submerged underwater
- Ex: Lotus and Elodea sp.
Xerophytes
- plants that live in a habitat that is hot and dry with a minimum presence of water such as desert
- Ex: Cactus and date palm

Question 5

Halophytes are plants that can live in a habitat with high _______ __ ____ and low _____ _____. This habitat is also exposed to high intensity of _____.

Answer 5

• content of salt
• oxygen content
• light

Question 6

What are the adaptations of leaves in halophytes?

Answer 6

• thick cuticle and sunken stomata can reduce the rate of transpiration
• succulent leaves for water storage
• has hydathodes to eliminate excess salt
• old leaves store salt and fall off when there is high salinity

Question 7

What are the adaptations of roots in halophytes?

Answer 7

• branches widely to support the plants in muddy soil and prevents plants from being uprooted due to strong wind
• hundreds of breathing roots that grow vertically upwards above the soil surface named pneumatophores
• pores called lenticels to enable gaseous exchange
• cell sap has high salinity than seawater it can receive water through osmosis

Question 8

Most hydrophytes have ______ roots that provide a large _____ ____ and trap air _____ to enable the plants to be lighter and stable.

Answer 8

• fibrous
• surface area
• bubbles

Question 9

Explain the adaptations of floating plants such as lotus ( hydrophytes ) in terms of leaves and roots condition.

Answer 9

• roots not anchored to the bottom of the lake
• broad, thin and flat leaves to absorb maximum sunlight
• most stomata are on the upper epidermis
• upper epidermis is also covered by a waterproof waxy cuticle
• stem of the plants consists of light tissue with air spaces known as aerenchyma tissues.

Question 10

Explain the adaptations of submerged plants such as Elodea sp.

Answer 10

• thin and small leaves to increase the total surface area per volume and increase the diffusion rate
• no stomata or cuticle
• small and hollow stems to help the plants to float upright and reduce water flow resistance

Question 11

Explain the adaptations of xerophytes.

Answer 11

• roots grow widely and penetrate deep into the soil to absorb water
• water and mineral salts are stored in the leaves, stems and roots
• stem of a cactus carries out photosynthesis
• small leaves with thick waxy cuticle which then modifies into thorns
• thorns reduces the total surface area exposed to the sun thus reducing water loss
• thorns also collect dew and are sharp to prevent being eaten by animals
• stomata embedded to reduce evaporation

Question 12

What are 3 types of root systems found in halophytes?

Answer 12

• cable root system
• buttress root system
• prop roots