NCERT Exercise

Draw a labelled diagram of a neuron.

Related Questions Tissues

The three types of muscle fibres are:Striated muscles, smooth muscles (unstriated muscle fibre), and cardiac muscles.

Striated muscle fibres

Unstriated muscle fibres

Cardiac muscle fibres

Give reasons for
(a) Meristematic cells have a prominent nucleus and dense cytoplasm but they lack vacuole.
Ans. Cells of meristematic tissue are capable of division. Hence, prominent nucleus and dense cytoplasm are present in these cells. Since these cells continuously undergo division hence they do not need to maintain a particular shape and store food. Due to this, vacuoles are not required in these cells.

(b) Intercellular spaces are absent in sclerenchymatous tissues.
Ans. Cell wall in sclerenchyma is lignified. Due to this, intercellular spaces are absent in sclerenchymatous tissues.

(c) We get a crunchy and granular feeling, when we chew pear fruit.
Ans. In a pear fruit, cells of scelerenhyma are small and called stone cells. We get the crunchy feeling due to these stone cells.

(d) Branches of a tree move and bend freely in high wind velocity.
Ans. Collenchyma is present at junction of a branch. Collenchyma provides rigidity with flexibility. Due to this, branches of tree move and bend freely in high wind velocity.

(e) It is difficult to pull out the husk of a coconut tree.
Ans. The husk of coconut tree is composed of sclerenhyma. Due this, the husk is very hard and is difficult to be pulled out.

Simple: Parenchyma/collenchyma/sclerenchyma

Complex: Phloem/xylem.

Simple permanent tissues are of three types:→ Parenchyma
→ Collenchyma

→ Sclerenchyma

Parenchyma tissue is of further two types:

• Aerenchyma

• Chlorenchyma

1. Which of the following tissues has dead cells?
(a) Parenchyma
(b) Sclerenchyma
(c) Collenchyma
(d) Epithelial tissue
Ans. (b) Sclerenchyma
Explanation: Sclerenchyma is entirely composed of dead cells. Tissues in others options are composed of live cells only.

2. Find out incorrect sentence
(a) Parenchymatous tissues have intercellular spaces
(b) Collenchymatous tissues are irregularly thickened at corners
(c) Apical and intercalary meristems are permanent tissues
(d) Meristematic tissues, in its early stage, lack vacuoles
Ans. (c) Apical and intercalary meristems are permanent tissues
Explanation: Meristematic tissues are not permanent tissues and hence option ‘c’ is incorrect statement.

3. Girth of stem increases due to
(a) apical meristem
(b) lateral meristem
(c) intercalary meristem
(d) vertical meristem
Ans. (b) lateral meristem
Explanation: Other meristems in options facilities growth in length, while lateral meristem facilities growth in girth.

4. Which cell does not have perforated cell wall?
(a) Tracheids
(b) Companion cells
(c) Sieve tubes
(d) Vessels
Ans. (b) Companion cells
Explanation: Perforated cell walls in cells (options a, c and d) are necessary to make channels for transport of water. Moreover, companion cells are live cells and hence do not have perforated cell wall.

5. Intestine absorbs the digested food materials. What type of epithelial cells are
responsible for that?
(a) Stratified squamous epithelium
(b) Columnar epithelium
(c) Spindle fibres
(d) Cuboidal epithelium
Ans. (b) Columnar epithelium
Explanation: Epithelium in option ‘a’ is present in skin and that in option ‘d’ is meant for structural support. Columnar epithelium facilities absorption. Tissue in option ‘c’ is not a type of epithelium.

6. A person met with an accident in which two long bones of hand were dislocated. Which among the following may be the possible reason?
(a) Tendon break
(b) Break of skeletal muscle
(c) Ligament break
(d) Areolar tissue break
Ans. (c) Ligament break
Explanation: Ligaments join a bone to another bone and hence ligament break can result in dislocation.

7. While doing work and running, you move your organs like hands, legs etc. Which among the following is correct?
(a) Smooth muscles contract and pull the ligament to move the bones
(b) Smooth muscles contract and pull the tendons to move the bones
(c) Skeletal muscles contract and pull the ligament to move the bones
(d) Skeletal muscles contract and pull the tendon to move the bones
Ans. (d) Skeletal muscles contract and pull the tendon to move the bones
Explanation: Skeletal muscles are responsible for voluntary movement and hence movement in hand is facilitated by contraction or relaxation in skeletal muscles. A tendon joins a bone to a muscle; so, option ‘d’ is correct.

8. Which muscles act involuntarily?
(i) Striated muscles
(ii) Smooth muscles
(iii) Cardiac muscles
(iv) Skeletal muscles
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
Ans. (b) (ii) and (iii)
Explanation: Skeletal muscles are voluntary. They are also striated. Smooth muscles and cardiac muscles are involuntary.

9. Meristematic tissues in plants are
(a) localised and permanent
(b) not limited to certain regions
(c) localised and dividing cells
(d) growing in volume
Ans. (c) localised and dividing cells
Explanation: Cells of meristematic tissue are dividing cells. Meristematic tissue is present only in those parts which needs to grow.

10. Which is not a function of epidermis?
(a) Protection from adverse condition
(b) Gaseous exchange
(c) Conduction of water
(d) Transpiration
Ans. (c) Conduction of water
Explanation: Conduction of water is a function of xylem and not of epidermis.

11. Select the incorrect sentence
(a) Blood has matrix containing proteins, salts and hormones
(b) Two bones are connected with ligament
(c) Tendons are non-fibrous tissue and fragile
(d) Cartilage is a form of connective tissue
Ans. (c) Tendons are non-fibrous tissue and fragile
Explanation: Tendons are fibrous tissue and are highly elastic and strong.

12. Cartilage is not found in
(a) nose
(b) ear
(c) kidney
(d) larynx
Ans. (c) kidney
Explanation: Kidney is composed of different kinds of epithelial tissues.

13. Fats are stored in human body as
(a) cuboidal epithelium
(b) adipose tissue
(c) bones
(d) cartilage
Ans. (b) adipose tissue
 Explanation: Another name of adipose tissue is fat tissue.
14. Bone matrix is rich in
(a) fluoride and calcium
(b) calcium and phosphorus
(c) calcium and potassium
(d) phosphorus and potassium
Ans. (b) calcium and phosphorus
Explanation: Bone cells are embedded in a hard matrix which is composed of calcium and phosphorus. 

15. Contractile proteins are found in
(a) bones
(b) blood
(c) muscles
(d) cartilage
Ans. (c) muscles
Explanation: Muscles have the ability of contraction and hence contractile proteins are found in them.