Biology ICSE Class 7 Important Questions Chapter 3 Tissues, Organs and Organ Systems in Plants and Animals
Extra Questions
Involuntary muscle :
- These muscles arc present in the internal organs of our body.
- These muscles have no stiiations.
- The cells are uninucleate.
- They help in the mov-ement of food, movement of urine from the urinary bladder and so on.
- They are spindle shaped.
Cardiac muscle :
- These muscles are present only in the heart
- These have dark and tight bands.
- The cells arc multi nucleate.
- They help in pumping of the blood for distribution to various parts of the body.
- They are cylindrical and branched.
Question 2.
What is meristematic tissue ? Mention its two characteristics and types.
Answer:
The group of actively dividing cells in plants form the meristemtatic tissue. Its characteristics are :
(i) The cells are small in size, cell wall is thin, nuclei are prominent and vacuoles are mostly absent.
(ii) The cells actively divide to form new cells.
Depending on location,
it is of two types –
(i) Apical meristematic tissue – Present at root and shoot tip and causes an increase in the height (length) of the plant.
(ii) Lateral meristematic tissue – It is present between xylem and phloem and leads to Increase in the thickness of a plant stem.
Question 3.
Name two types of permanent tissues in plants.
Answer:
(i) Simple permanent tissue (provides support and protection.)
(ii) Complex permanent tissue (conducts nutrients and water).
Question 4.
Differentiate between xylem and phloem.
Answer:
Xylem :
- It conducts water upwards from roots to the shoot system.
- It is made of mostly dead cells.
- It is located towards the inner side of the vascular bundle.
Phloem :
- It transports food materials from leaves to other parts of the plant.
- It is made of living cells.
- It is located on the outer side of the vascular bundle.
Question 5.
What forms the annual rings in the trees in their stems?
Answer:
New xylem tissue keeps getting added to a growing plant as a result of actively dividing cells in cambium. Due to increased and decreased growth activity in spring and autumn, alternating patterns of growth are seen in xylem tissue of big trees season after season. These are called annual rings.
Question 6.
Define gland.
Answer:
A gland is a group of cells or an organ in the body that produce certain substances to coordinate specific metabolic activities.
Question 8.
Write the comparative study of characteristic features of the three types of muscular tissue.
Answer:
Voluntary muscles :
- Shape : Cylindrical and without branches
- Bands (Striations) : Dark and light bands (striations) are present
- Nucleus : Multinucleate
- Control: These are under your control or will
- Efficiency : Attached to the bones and get tired when over-worked
- Function : Help in the movement of the bones
- Location : Present in hands, legs, tongue, jaws, body (trunk) and so on
Involuntary muscles :
- Spindle-shaped
- No striations are present
- Uninucleate
- These are not under your control or will
- Present in the walls of internal organs of alimentary canal, urinary bladder and so on
- Help in the movement of food, movement of urine from urinary bladder and so on
- Present in the walls of the stomach, intestines, urinary bladder and artieiies.
Cardiac muscles :
- Cylindrical and branched
- Dark and light bands are present
- Uninucleate
- These are not under your control or will
- Work tirelessly and continuously throughout the life
- Cause the rhythmic movement of the heat resulting in circulation of blood in the body
- Present only in the heart
Question 9.
Explain the structure of a nerve cell or neuron.
Answer:
Each neuron is a specialised structure having a central part called the cell body or cyton and numerous thread like branches extending from all sides of the cells body called dendrons. Dendrons further divide to form dendrites. One of the extension is larger than the rest and called axon.
Question 10.
Name two organs systems in plants.
Answer:
(i) Root system comprising of primary and secondary roots
(ii) Shoot system comprising of stems, leaves and flowers.
Question 11.
Why don’t we wake up in the morning with a layer of mould growing on our skin ?
Answer:
It is because our skin secretes antibacterial substances which kill the bacteria and spores that land on our skin.
Question 12.
Name major organs and functions of
- Excretory system
- Nervous system
- Intergumentary system
- keletal system
Answer:
- Major organs of excretory system are kidneys, skin and lungs. Function – Removes waste products.
- Major organs of nervous system are nerves, brain and spinal cord.
Function – Receives and transports messages throughout the body, coordinates body parts. - Major organs of integumentary system are skin, nails and hair. Function – Protects, prevents drying out, removes some wastes, helps to regulate body temperature.
- Major organs of skeletal system are bones. Function – Supports, allows movement, protects, stores minerals, produces blood cells.
I. Fill in the blanks.
(i) In leaves, the epidermis has special cells called …………. that control the opening and closing of stomata.
Answer:
In leaves, the epidermis has special cells called guard cells that control the opening and closing of stomata.
(ii) In big trees, the outer covering of the tree trunk is multi-layered and called …………
Answer:
In big trees, the outer covering of the tree trunk is multi-layered and called periderm.
(iii) Collenchyma has cell walls thickened at the corners due to the presence of ……….. and ……….
Answer:
Collenchyma has cell walls thickened at the comers due to the presence of cellulose and pectin.
(iv) Xylem and phloem together are called the
Answer:
Xylem and phloem together are called the vascular bundle.
(v) The light and dark bands in voluntary muscles are due ………… to the presence of special protein filaments of ……….. and that contract and relax and muscles to
produce movement.
Answer:
The light and dark bands in voluntary muscles are due to the presence of special protein filaments of Actin and Myosin that contract and relax and muscles to produce movement.
(vi) Muscle cells contain specialized cytoplasm called ………… and are bound by a think cell membrane called ………..
Answer:
Muscle cells contain specialized cytoplasm called sarcoplasm and are bound by a think cell membrane called
sarcolemma.
(vii) Many neurons or nerve fibres bound together contitute to form a ………..
Answer:
Many neurons or nerve fibres bound together contitute to form a nerve.
(viii) The message is carried along a neutron in form of’ impulses and in …………… direction only.
AnsWER:
The message is carried along a neutron in form of impulses and in one direction only.
(ix) Messages to the neuron are conveyed by the …………. while the messages from the neuron are conveyed through the
Answer:
Messages to the neuron are conveyed by the dendrites while the messages from the neuron are conveyed through the axon.
(x) In cartilage, the ground substance or matrix is filled ………….. with cells called white in bones, is filled with cells called …………
Answer:
In cartilage, the ground substance or matrix is filled with cells called chondrocytes white in bones, is filled with cells called
osteocytes.
(xi) In bones, matrix is arranged in the form of concentric layers around a central canal calle ………….. canal.
Ans. hi bones, matrix is arranged in the form of concentric layers around a central canal called Haversian canal.
(xii) Leaves, stems and roots are plant organs while flower is …………… plant organ.
Answer:
Leaves, stems and roots are vegetative plant organs while flower is reproductive plant organ.
(xiii) …………. is a complex substance that forms thickening in sclerenchyma cells.
Answer:
Lignin is a complex substance that forms thickening in sclerenchyma cells.
ICSE Class 7 Biology Important Questions