शनिवार, 29 जुलाई 2017


(Page No. 69)
1. What is a tissue?
Ans. It is a group of cells similar in origin and structure and they are specialized to perform a particular function like muscle cells in our body form the muscle tissue that bring about body movements (specific function).

2. What is the utility of tissues in multi-cellular organisms?
Ans. There is a clear cut division of labour in multicellular organisms i.e. different parts of the body of a multicellular organism perform specific functions. For example, brain controls all other parts of body, heart pumps blood to all parts of body, kidneys remove waste materials from body, sense organs collect information from external sources for sensory perception etc. All these functions would never be possible without formation of tissues in multicellular organisms.

(Page No. 74)
1. Name types of simple tissues.
Ans. The simple tissues (found in plants) are of following three types:
i) parenchyma
ii) collenchymas
iii) Sclerenchyma

2. Where is apical meristem found?
Ans. The apical meristem is found at the apex (growing tips) of the stem and roots.

3. Which tissue makes up the husk of coconut?
Ans. Sclerenchymatous tissue.

4. What are the constituents of phloem?
Ans. The constituents of phloem are: sieve tubes, companion cells, phloem parenchyma, phloem fibres (bast).

(Page No. 78)
1. Name the tissue responsible for movement in our body.
Ans. Muscle/muscular tissue.

2. What does a neuron look like?
Ans. A neuron comprises of a cell body (cyton) along with one or more short branches(Dendron) and one hair like long branch (axon).

3. Give three features of cardiac muscles.
Ans. v Cardiac muscles are involuntary i.e. they don’t work under our will.
i. Its cells are cylindrical, branched, striated and uninucleate.
ii. It shows rhythmic contraction and relaxation throughout the person’s life.

4. What are the functions of areolar tissue?
Ans. Areolar tissue is a kind of filler tissue found between skin and muscles, around our blood vessels and nerve cells and also in the bone marrow. Its functions are therefore
i) To fill the space inside organs.
ii) To help in repair and maintenance of nearby tissues/organs.
iii) To support and prevent injuries to internal organs.

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