Class 9 BiologyChapter 3Revise
Revise tissues
30 flashcards that come back when due, 19 practice questions in exam styles, and one page to print.
Flashcards
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What is a tissue?
A group of cells, similar in structure, that work together to perform a specific function.
The levels of organisation, smallest first?
Cell, tissue, organ, organ system, organism.
Division of labour in a many-celled body?
Different tissues do different jobs, which makes the body more efficient at complex life processes.
Why are plant cells rigid and animal cells flexible?
Plant cells have a rigid cell wall (plants stay in one place and need support); animal cells have none, so they change shape, which helps movement.
What is meristematic tissue?
A tissue of actively dividing cells that adds new cells for growth.
The three meristems and what each does?
Apical (root and shoot tips): length. Lateral (ring in the stem): girth. Intercalary (base of internode or above a node): regrowth after cutting.
Activity 3.1: what happens when onion root tips are cut?
The cut roots stop growing in length, while the uncut ones keep growing. Roots grow only from their tips.
What can annual growth rings tell us?
The approximate age of the tree (about one ring a year) and the growing conditions: wide rings in good years, narrow in poor ones.
Node and internode?
Node: where leaves or branches arise on a stem. Internode: the part of the stem between two nodes.
Features of meristem cells?
Small, thin walled, large prominent nucleus, dense cytoplasm, usually no vacuole, tightly packed with little or no space between.
Differentiation?
The process by which cells from a meristem lose the power to divide and specialise for one job, becoming permanent tissue.
Simple versus complex permanent tissue?
Simple: one type of cell (parenchyma, collenchyma, sclerenchyma). Complex: more than one type (xylem, phloem).
Three special features of the epidermis?
A waxy cuticle of cutin (less water loss), hair-like outgrowths such as root hairs (absorption), and stomata in leaves (gas exchange, transpiration).
How does transpiration help the plant?
Water lost through the stomata creates a transpiration pull that draws water up the xylem; it also helps remove wastes.
Parenchyma, collenchyma, sclerenchyma in one line each?
Parenchyma: living, thin walls, loose, stores food. Collenchyma: living, corners thickened with pectin, flexible. Sclerenchyma: thick lignin walls, mostly dead, hard.
The four kinds of cells in xylem?
Tracheids, vessels, xylem parenchyma (the only living ones) and xylem fibres.
The four kinds of cells in phloem?
Sieve tubes, companion cells, phloem parenchyma and phloem fibres. Mostly living cells.
What do companion cells do?
They are specialised parenchyma that regulate the sieve tube cells and monitor the loading and unloading of sugars.
The three plant tissue systems?
Dermal (outer covering), ground (parenchyma, collenchyma, sclerenchyma) and vascular (xylem and phloem).
The four main types of animal tissue?
Epithelial, connective, muscular and nervous.
Thin flat epithelium versus layered epithelium?
One layer of thin flat cells for fast exchange (lungs, blood vessels); many layers for protection (skin, mouth, oesophagus).
Why is blood fluid but bone hard, if both are connective tissue?
Their matrix differs: watery and jelly-like in blood, hard and rigid (with calcium and phosphorus compounds) in bone.
Jobs of RBCs, WBCs and platelets?
RBCs: carry oxygen, with iron-rich haemoglobin. WBCs: gather at infections. Platelets: help blood clot.
Tendon versus ligament?
Tendon: muscle to bone. Ligament: bone to bone, gives stability and limits movement.
Skeletal, smooth, cardiac: control and nuclei?
Skeletal: voluntary, many nuclei, striated. Smooth: involuntary, one nucleus, no striations. Cardiac: involuntary, one nucleus, branched, faint striations.
Three main parts of a neuron?
Cell body (nucleus, controls the cell), dendrites (receive signals) and axon (carries messages away, ending in axon terminals).
How does a muscle move a bone?
It contracts and pulls; the tendon passes the force to the bone, which moves at a joint, under the control of the nervous system.
About what share of an adult's body weight is skeleton?
About 12 to 15 per cent on average.
Four types of joints with an example each?
Ball and socket: shoulder. Hinge: elbow, knee. Pivot: skull on the backbone. Fixed: between skull bones.
What did F. C. Steward show in 1958?
Single phloem cells of carrot could regenerate whole plants: totipotency, by dedifferentiation and redifferentiation.
Practice questions
Questions in the styles CBSE uses: multiple choice, assertion and reason, case based and labelling a diagram. Each answer comes with the reason. Send any question to a friend; the link opens it here and carries nothing about you.
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1Multiple choice Meristematic tissue
A cell is small and thin walled, with a big nucleus and dense cytoplasm, and no vacuole. Where are you most likely to find it?
These are features of meristem cells, and the apical meristem sits at the root tip. Cork, husk and vessels are made of dead cells.
Show the answer
B. These are features of meristem cells, and the apical meristem sits at the root tip. Cork, husk and vessels are made of dead cells.
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2Multiple choice Meristematic tissue
After a hedge is trimmed, many new side branches appear. They grow from:
Removing the tips stops growth in length; new branches arise at the nodes, where intercalary meristem is found.
Show the answer
B. Removing the tips stops growth in length; new branches arise at the nodes, where intercalary meristem is found.
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3Multiple choice Permanent tissue
A white flower on a cut stem is stood in water with blue ink. After a few hours its petals have blue veins. Which tissue carried the ink up?
Xylem carries water and what is dissolved in it upwards from the base to the leaves and flowers.
Show the answer
B. Xylem carries water and what is dissolved in it upwards from the base to the leaves and flowers.
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4Multiple choice Permanent tissue
What makes a walnut shell so hard?
Sclerenchyma cells have thick walls stiffened with lignin; it forms hard coverings of seeds and nuts.
Show the answer
C. Sclerenchyma cells have thick walls stiffened with lignin; it forms hard coverings of seeds and nuts.
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5Multiple choice Permanent tissue
A water hyacinth floats on a pond. Which tissue helps it stay afloat?
Air-filled spaces in its parenchyma act like floats.
Show the answer
B. Air-filled spaces in its parenchyma act like floats.
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6Multiple choice Animal tissues
Food rubs against the lining of the oesophagus as you swallow. What kind of epithelium suits this lining?
Protective epithelium has many layers that resist friction and injury: skin, mouth and oesophagus.
Show the answer
B. Protective epithelium has many layers that resist friction and injury: skin, mouth and oesophagus.
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7Multiple choice Animal tissues
Long, unbranched, cylindrical cells with many nuclei and light and dark bands, attached to bones. This is:
Skeletal muscle fibres are long, cylindrical, unbranched, multinucleate and striated.
Show the answer
C. Skeletal muscle fibres are long, cylindrical, unbranched, multinucleate and striated.
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8Multiple choice Musculoskeletal system
A teacher weighs 70 kg. Taking bone as 12 per cent of body weight, about how much of the weight is bone?
0.12 × 70 = 8.4 kg.
Show the answer
B. 0.12 × 70 = 8.4 kg.
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9Multiple choice Joints and skeleton
A bowler swings an arm in a full circle before releasing the ball. Which joint allows this?
Only the ball and socket joint at the shoulder allows circular movement of the arm.
Show the answer
B. Only the ball and socket joint at the shoulder allows circular movement of the arm.
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10Multiple choice Joints and skeleton
Why can the rib cage expand when we breathe in?
Flexible cartilage joins the ribs, letting the cage expand and contract and change the space in the chest.
Show the answer
B. Flexible cartilage joins the ribs, letting the cage expand and contract and change the space in the chest.
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11Assertion and reason Meristematic tissue
Assertion (A) Cutting off the tip of a growing root stops the root getting longer.
Reason (R) The apical meristem, which adds cells for growth in length, is at the root tip.
Both are true, and removing the meristem at the tip is exactly why growth in length stops.
Show the answer
A. Both are true, and removing the meristem at the tip is exactly why growth in length stops.
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12Assertion and reason Permanent tissue
Assertion (A) Xylem parenchyma is a living tissue.
Reason (R) Tracheids and vessels are mainly sclerenchymatous.
Both statements are true, but the nature of tracheids and vessels does not explain why xylem parenchyma is living.
Show the answer
B. Both statements are true, but the nature of tracheids and vessels does not explain why xylem parenchyma is living.
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13Assertion and reason Permanent tissue
Assertion (A) Collenchyma gives support along with flexibility.
Reason (R) Collenchyma walls are thickened evenly all over with lignin.
A is true. R is false: collenchyma is thickened unevenly, at the corners, with pectin.
Show the answer
C. A is true. R is false: collenchyma is thickened unevenly, at the corners, with pectin.
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14Assertion and reason Animal tissues
Assertion (A) Ligaments let a joint move further than its normal range.
Reason (R) Ligaments connect bone to bone.
A is false: ligaments limit movement and help prevent dislocation. R is true.
Show the answer
D. A is false: ligaments limit movement and help prevent dislocation. R is true.
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15Case based Meristematic tissue
A season in the school garden
The gardening club mows the school lawn every week and trims the hedge once a month. In the corner stands an old mango tree; a branch that fell in a storm shows rings on its cut end, some wide and some narrow.
(i) Why does the lawn keep growing back after mowing?
The mower removes the tips, but the intercalary meristem low on the stems keeps dividing.
Show the answer
B. The mower removes the tips, but the intercalary meristem low on the stems keeps dividing.
(ii) The rings on the cut branch were made by which tissue?
The lateral meristem, a ring of dividing cells, adds layers each year and thickens the stem.
Show the answer
B. The lateral meristem, a ring of dividing cells, adds layers each year and thickens the stem.
(iii) What do the narrow rings most likely show?
Narrow rings record unfavourable years; wide rings record favourable ones.
Show the answer
A. Narrow rings record unfavourable years; wide rings record favourable ones.
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16Case based Animal tissues
A football match
Kabir scraped his knee during a match. It bled for a minute and then stopped. Two days later the scrape was red and slightly swollen, with a little pus. By the weekend it had healed, and he ran a race, finishing out of breath and red in the face.
(i) What helped stop the bleeding?
Platelets gather at a wound and help the blood clot.
Show the answer
B. Platelets gather at a wound and help the blood clot.
(ii) Which blood cells gathered at the infected scrape?
WBCs collect at infections, causing redness, swelling and pus.
Show the answer
C. WBCs collect at infections, causing redness, swelling and pus.
(iii) Why was Kabir breathing hard after the race?
Hard working muscles use extra oxygen, so you breathe faster and more blood is pumped to them.
Show the answer
A. Hard working muscles use extra oxygen, so you breathe faster and more blood is pumped to them.
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17Case based Joints and skeleton
One cell, one plant
A scientist took tiny pieces of phloem from a carrot and grew them in a liquid medium with sugars and hormones. Single cells broke free and divided into a mass of unspecialised cells. These later formed roots and a shoot, and finally grew into a whole carrot plant.
(i) The phloem cells regaining the ability to divide is called:
Specialised cells going back to dividing is dedifferentiation.
Show the answer
B. Specialised cells going back to dividing is dedifferentiation.
(ii) The ability of a single cell to grow into a whole plant is:
This is totipotency, which F. C. Steward showed with carrot phloem in 1958.
Show the answer
A. This is totipotency, which F. C. Steward showed with carrot phloem in 1958.
(iii) Which is a sensible use of this idea?
Regenerating plants from cultured cells lets growers raise many plants from a small amount of tissue.
Show the answer
B. Regenerating plants from cultured cells lets growers raise many plants from a small amount of tissue.
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18Label the diagram Permanent tissue
Label the tissues in this T.S. of a sunflower stem.
From outside in: epidermis, collenchyma just below it, then loose parenchyma. In each bundle, the sclerenchyma cap is outermost, then phloem, then the lateral meristem, then xylem towards the centre.
Show the answer
1: Epidermis, 2: Collenchyma, 3: Parenchyma, 4: Sclerenchyma, 5: Phloem, 6: Xylem. From outside in: epidermis, collenchyma just below it, then loose parenchyma. In each bundle, the sclerenchyma cap is outermost, then phloem, then the lateral meristem, then xylem towards the centre.
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19Label the diagram Animal tissues
Label the parts of this neuron.
Dendrites branch from the cell body, which holds the nucleus. The long axon carries the message away and ends in axon terminals.
Show the answer
1: Dendrites, 2: Cell body, 3: Nucleus, 4: Axon, 5: Axon terminals. Dendrites branch from the cell body, which holds the nucleus. The long axon carries the message away and ends in axon terminals.
Memory aids
Memory aid
Can Tiny Organs Organise Our bodies?
Cell, Tissue, Organ, Organ system, Organism
Small to big, one rung at a time.
Memory aid
Tip, side, in between
Apical: tip, length. Lateral: side, girth. Intercalary: in between, regrowth.
Match the name to where the meristem sits.
Memory aid
P, C, S: store, sway, stiff
Parenchyma stores, collenchyma sways, sclerenchyma is stiff
Thin walls; pectin corners; lignin walls and mostly dead cells.
Memory aid
Xylem up, phloem food
Xylem: water up from roots. Phloem: food from leaves.
Xylem is the express lift from the basement; phloem is the kitchen delivering to every room.
Memory aid
Ligament links, tendon tugs
Ligament: bone to bone. Tendon: muscle to bone.
The L of ligament links two bones; the tendon tugs the bone when the muscle pulls.
Memory aid
Strong, slow, constant
Skeletal strong and voluntary; smooth slow; cardiac constant
Only skeletal muscle obeys your will; the heart never takes a break.
Memory aid
Ball, hinge, pivot, fixed
All, one, turn, none
Ball and socket moves in all directions, hinge in one, pivot turns, fixed does not move.
One page summary
One page summary
Class 9 Biology, Chapter 3: Tissues in Action
Everything in the chapter on one page.
Tissues (opening, 3.1)
- Tissue: similar cells, one shared job.
- Cell, tissue, organ, organ system, organism.
- Division of labour makes the body efficient.
- Plants: fixed, rigid cell walls, photosynthesis.
- Animals: move, flexible cells, digest food.
Meristems (3.2 to 3.2.3)
- Apical: root and shoot tips, length (Activity 3.1).
- Lateral: ring in stem, girth; annual rings.
- Intercalary: node or internode base; regrowth after cutting.
- Cells: small, thin walls, big nucleus, dense cytoplasm, no vacuole.
- Differentiation: meristem becomes permanent tissue.
Permanent tissues (3.2.4)
- Simple: one cell type. Complex: several.
- Epidermis: cuticle, root hairs, stomata.
- Parenchyma stores; collenchyma flexes (pectin); sclerenchyma hard (lignin, dead).
- Xylem: tracheids, vessels, parenchyma, fibres; water up.
- Phloem: sieve tubes, companion cells, parenchyma, fibres; food.
- Systems: dermal, ground, vascular.
Animal tissues (3.3 to 3.3.4)
- Epithelial, connective, muscular, nervous.
- Epithelium: thin for exchange, layered for protection.
- Blood: plasma 55%, RBC, WBC, platelets.
- Bone (rigid), cartilage (flexible), tendon (muscle to bone), ligament (bone to bone).
- Skeletal voluntary; smooth and cardiac involuntary.
- Neuron: dendrites, cell body, axon, terminals.
Muscles and bones (3.4, 3.4.1)
- Bones, muscles, joints, cartilage, tendons, ligaments.
- Muscles pull through tendons; bones move at joints.
- Controlled by the nervous system.
- Skeleton about 12 to 15 per cent of body weight.
- Joint: junction of two or more bones.
Joints and skeleton (3.5, 3.6)
- Ball and socket: shoulder. Hinge: elbow, knee.
- Pivot: skull on backbone. Fixed: skull bones.
- Vertebrae with cartilage discs; 12 pairs of ribs.
- Yoga, posture, food, exercise keep bones healthy.
- Steward 1958: carrot cell to plant, totipotency.
- Agrobacterium: from crown gall to gene tool.
numford.com. Section numbers follow NCERT Exploration, Grade 9; the wording is our own.