Karishma visited Egypt with her parents where she went on a tour of the Sahara
desert. She didn’t know that plants could also grow in the desert. She went and
tore a leaf from one plant and found that they were very thick. When she was
finally able to tear one small part, she found that the inside of the leaf was fresh
and watery.
4
a) Why are the leaves of plants that grow in deserts thick ?
b) Karishma sees that there is a waxy coating on the epidermis of the leaf. What is
the name of this coating and what is its function ?
c) Define transpiration.
d) As plants grow older, the outer protective tissue undergoes certain changes. A
strip of secondary meristem replaces the epidermis of the stem. Name this
tissue. Write any one characteristic of this tissue.
e) Draw a surface view of the epidermal layer of cells showing stomata. Tissues class 9 ans
Answers
a) The leaves and stems of many desert plants have a thick, waxy covering. This waxy substance does not cover the stomata, but it covers most of the leaves, keeping the plants cooler and reducing evaporative loss. Small leaves on desert plants also help reduce moisture loss during transpiration.
b)The waxy covering on plant leaves, young stems, and fruit is called the "cuticle". It is composed of cutin, a wax-like material produced by the plant that is chemically a hydroxy fatty acid. The purpose of this covering is to help the plant retain water
c)Transpiration is the evaporation of water from plants. ... This transpired water must be replaced by the transport of more water from the soil to the leaves through the xylem of the roots and stem.
d)As the plants grow older, the outer protective tissue (i.e., epidermis) undergoes certain changes. A strip of secondary moisten, called halogen or cork cambium replaces the epidermis of the stem.
sorry, don't know question no 5
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