Biology questions, chapter 1

Nama / NameKelas / ClassTarikh / Date

Organisation of Plant Tissues and Growth

46 marks. Use Practice to check each answer as you go, or Exam to answer everything against the clock first.

Section A: objective questions

12 marks

Choose the best answer for each question.

Question 1

Which plant tissue consists of actively dividing cells that divide by mitosis?

Epidermal tissue
Meristematic tissue
Ground tissue
Vascular tissue

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Meristematic tissues are actively dividing tissues. The other three are permanent tissues, which have already differentiated.

For the teacher: Remembering, low difficulty, standard 1.1

Textbook p. 4

Question 2

Which tissue has dead cells with lignin in the walls and transports water and mineral salts?

Phloem
Collenchyma
Parenchyma
Xylem

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Xylem is made of dead, hollow cells whose walls contain lignin; it carries water and mineral salts. Phloem is living.

For the teacher: Remembering, low difficulty, standard 1.1

Textbook p. 5

Question 3

A tissue is made of living cells with walls of pectin and hemicellulose. It gives flexible support to the plant. What is this tissue?

Collenchyma
Sclerenchyma
Parenchyma
Xylem

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Collenchyma has walls of pectin and hemicellulose, thicker than parenchyma, giving support and elasticity. Sclerenchyma is dead and rigid.

For the teacher: Understanding, low difficulty, standard 1.1

Textbook p. 5

Question 4

What is the main function of the sieve tubes in phloem?

To carry water from the roots to the leaves
To reduce water loss through the leaf surface
To carry sugars made in photosynthesis to storage organs such as roots and tubers
To give mechanical strength to mature plant parts

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Phloem sieve tubes carry the sugars produced by photosynthesis from the leaves to storage organs. Water is carried by xylem.

For the teacher: Understanding, low difficulty, standard 1.1

Textbook p. 5

Question 5

Guard cells and root hair cells are modified from which tissue?

Ground tissue
Vascular tissue
Epidermal tissue
Meristematic tissue

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Guard cells and root hair cells are modified epidermal cells (textbook Table 1.1).

For the teacher: Understanding, low difficulty, standard 1.1

Textbook p. 5

Question 6

Where are the apical meristems found?

At the tips of shoots and roots
Between the xylem and the phloem
Under the epidermis of the stem
In the pith of the stem

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Apical meristems are at the shoot and root tips. Vascular cambium lies between xylem and phloem; cork cambium lies under the epidermis.

For the teacher: Remembering, low difficulty, standard 1.2

Textbook p. 6

Question 7

How do the cells in the zone of cell elongation increase in size?

They divide repeatedly by mitosis
Lignin is deposited in their walls
They form cork cells on the outside
Water enters by osmosis and small vacuoles fuse into a large vacuole

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Water diffuses in by osmosis, small vacuoles fuse into one large vacuole, and the pressure pushes the cell wall outwards and lengthens the cell.

For the teacher: Understanding, low difficulty, standard 1.2

Textbook p. 8

Question 8

Where is the vascular cambium located in a stem?

Under the epidermis
Between the xylem and phloem in the vascular bundles
At the tip of the stem
In the centre of the pith

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The vascular cambium lies between xylem and phloem. The cork cambium lies under the epidermis.

For the teacher: Understanding, low difficulty, standard 1.2

Textbook p. 10

Question 9

A tree in a temperate country has dark rings in its stem. Which statement explains the formation of a dark ring?

It forms in summer when the secondary xylem is smaller with thicker walls
It forms in spring when the secondary xylem is larger with thinner walls
It forms in spring when the secondary xylem is smaller with thinner walls
It forms in summer when the secondary xylem is larger with thinner walls

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In spring there is enough water and sunlight, so large thin-walled xylem forms (bright). In summer growth is less suitable and small thick-walled xylem forms (dark).

For the teacher: Applying, medium difficulty, standard 1.2

Textbook p. 12

Question 10

Which statement is true of secondary growth only, and not primary growth, in eudicots?

It involves cell division by mitosis
It occurs at the apical meristems
It increases the circumference of stems and roots and forms annual growth rings
It increases the size of the plant permanently

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Secondary growth is radial, thickens the stem and root, and forms growth rings. Mitosis and permanent growth are shared; apical meristems belong to primary growth.

For the teacher: Analysing, medium difficulty, standard 1.2

Textbook p. 15

Question 11

Which plant is a biennial plant?

Paddy
Hibiscus
Mango
Carrot

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Carrot (also cabbage and silver cock's comb) is biennial. Paddy is annual; hibiscus and mango are perennial.

For the teacher: Remembering, low difficulty, standard 1.3

Textbook p. 18

Question 12

Diagram 1 shows the growth curve of an annual plant. Why does the dry mass decrease in the first two weeks?

Line graph of dry mass against time for an annual plant — Diagram 1

The plant sheds its leaves and flowers
Food stored in the cotyledon is used for germination before the leaves can photosynthesise
The rate of photosynthesis is very high
The seeds are dispersed

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Before leaves emerge, the seedling uses the food stored in the cotyledon, so dry mass falls. Leaf shedding and seed dispersal cause the later decrease.

For the teacher: Analysing, medium difficulty, standard 1.3

Textbook p. 19

Section B: structured questions

34 marks

Answer all questions. Write your answers in the spaces provided.

Question 13

Diagram 2 shows the position of permanent tissues in a leaf, a stem and a root.

Cross sections of a leaf, a stem and a root with epidermal tissue, ground tissue, xylem and phloem labelled — Diagram 2

[1 mark] (a)State one function of the cuticle on the epidermal tissue of a leaf.

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Any 1 points

Reduces water loss through evaporation (transpiration)1
Protects the leaf from mechanical injury and pathogens1

Tick each point you got.

[2 marks] (b)Name two modified epidermal cells and state the function of each.

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Guard cells: control the opening of the stoma1
Root hair cells: increase the surface area of the root for absorption of water and mineral salts1

Tick each point you got.

[2 marks] (c)Explain how the structure of xylem is adapted to its function.

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Dead, hollow, elongated cells without cytoplasm joined end to end form continuous vessels, so water flows from roots to leaves1
Walls contain lignin, giving strength and support1

Tick each point you got.

For the teacher: Understanding, low difficulty, standard 1.1

Textbook p. 4

Question 14

A root tip of a seedling has three zones of cell growth.

[2 marks] (a)Name the zone where the cells divide by mitosis, and the zone where the cells become specialised.

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Zone of cell division1
Zone of cell differentiation1

Tick each point you got.

[2 marks] (b)Explain how the cells in the zone of cell elongation increase in size.

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Water enters the cells by osmosis and nutrients are absorbed1
Small vacuoles fuse to form a large vacuole, which pushes against the cell wall and lengthens the cell1

Tick each point you got.

[1 mark] (c)Give one specialised cell formed from the epidermis in the root.

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Root hair cell1

Tick each point you got.

For the teacher: Understanding, low difficulty, standard 1.2

Textbook p. 8

Question 15

Diagram 3 shows the secondary growth of a eudicot stem over three years.

Stem cross sections in the first, second and third year showing secondary growth — Diagram 3

[1 mark] (a)Name the lateral meristem that divides to form secondary xylem and secondary phloem.

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Vascular cambium1

Tick each point you got.

[2 marks] (b)Explain why the epidermis cracks and is shed.

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Secondary xylem is added, so the circumference of the stem increases1
The epidermis is stretched until it cracks and is shed1

Tick each point you got.

[2 marks] (c)State how the stem is protected after the epidermis is shed.

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Cork cambium divides to form cork cells on the outer side1
The cork layer protects the stem from insects and pathogens1

Tick each point you got.

For the teacher: Understanding, low difficulty, standard 1.2

Textbook p. 11

Question 16

A stem of a tree from a temperate climate shows 7 pairs of bright and dark rings.

[1 mark] (a)Estimate the age of the tree.

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7 years1

Tick each point you got.

[1 mark] (b)Which season forms the bright ring?

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Spring1

Tick each point you got.

[2 marks] (c)Explain why the bright and dark rings are different.

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Spring: enough water and sunlight, so secondary xylem is large with thin walls (bright)1
Summer: growth is unsuitable, so secondary xylem is small with thick walls (dark)1

Tick each point you got.

For the teacher: Applying, medium difficulty, standard 1.2

Textbook p. 12

Question 17

Compare primary growth and secondary growth in eudicots.

[2 marks] (a)State two similarities.

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Any 2 points

Both increase the size of the plant permanently1
Both occur in woody plants1
Both involve cell division by mitosis1

Tick each point you got.

[2 marks] (b)State two differences.

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Any 2 points

Primary growth at apical meristem; secondary growth at lateral meristem (vascular cambium and cork cambium)1
Primary growth is longitudinal and increases length; secondary growth is radial and increases thickness1
Primary growth has no annual rings or woody tissue; secondary growth has annual rings and woody tissue1

Tick each point you got.

For the teacher: Analysing, high difficulty, standard 1.2

Textbook p. 15

Question 18

Diagram 4 shows the dry mass of an annual plant over 24 weeks.

Line graph of dry mass against time: 10 g at week 0, 8 g at week 2, 30 g at week 10, 48 g from week 18 to 20, 44 g at week 24 — Diagram 4

[1 mark] (a)State the shape of the growth curve.

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Sigmoid curve1

Tick each point you got.

[1 mark] (b)Calculate the increase in dry mass from week 10 to week 18.

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48 − 30 = 18 g1

Tick each point you got.

[2 marks] (c)Explain why the dry mass is constant from week 18 to week 20.

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The plant is mature1
The rate of growth is zero1

Tick each point you got.

[2 marks] (d)Explain why the dry mass decreases after week 20.

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Ageing and a lower rate of photosynthesis1
Leaves and flowers are shed / seeds are dispersed1

Tick each point you got.

For the teacher: Analysing, medium difficulty, standard 1.3

Textbook p. 19

Question 19

A farmer notices that paddy plants die after harvest, but the grass in the field keeps growing for many years.

[2 marks] (a)Explain why the growth curve of a perennial plant consists of a series of small sigmoid curves.

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Growth occurs throughout the lifespan, with one sigmoid curve each year1
Growth is fast in spring and summer (high light increases photosynthesis) and slows in winter1

Tick each point you got.

For the teacher: Applying, medium difficulty, standard 1.3

Textbook p. 19

Question 20

A forestry department wants to tell visitors why trees that undergo secondary growth are valuable. Write three points for its brochure.

[3 marks] (a)Write three points.

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Any 3 points

Strong, hard timber (e.g. meranti, cengal) for houseboats, furniture, fences and doors1
Annual rings make furniture look attractive / decorative items1
Wood and bark give resin and oil for varnish, adhesive, perfume and medicine1
Fruits such as mango and mangosteen and decorative plants bring income1

Tick each point you got.

For the teacher: Creating, high difficulty, standard 1.2

Textbook p. 16

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