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CIE iGCSE Co-Ordinated Science B3.2 Osmosis Exam Style Questions Paper 3

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Question

(a) Fig. 1.1 is a diagram of a plant cell.
Fig 1.1 plant cell diagram
(i) State the letter in Fig. 1.1 that identifies the part:
that strengthens the cell …………………..
where photosynthesis occurs …………………..
where genetic material is stored. …………………..
(ii) State two letters that identify cell structures in Fig. 1.1 that are present in both animal and plant cells.
(b) Fig. 1.2 is a photomicrograph of a plant cell.
Fig 1.2 photomicrograph of plant cell
(i) State the two values you need to be able to calculate the actual size of the plant cell.
(ii) Complete the sentences to describe the effect of immersion in pure water on the plant cell in Fig. 1.2. Use words or phrases from the list. Each word or phrase may be used once, more than once or not at all.
amino acids, assimilation, glucose, osmosis, partially permeable, respiration, vacuole, water
There is an increase in the size of the plant cell ……………………………… .
This is because ……………………………… enters the plant cell through the ……………………………… membrane.
This process is called ……………………………… .

Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):

• Topic B2.1 — Cell structure (Part (a)(i), (a)(ii))
• Topic B2.2 — Size of specimens (Part (b)(i))
• Topic B3.2 — Osmosis (Part (b)(ii))

▶️ Answer/Explanation

(a)(i) D ; B ; E

D is the cell wall, which gives the plant cell mechanical strength and rigidity.
B is a chloroplast, the organelle where photosynthesis takes place.
E is the nucleus, which stores the cell’s genetic material (DNA).

(a)(ii) Any two from: A, E, F

A (mitochondria), E (nucleus) and F (cell membrane) are organelles found in both plant and animal cells.
By contrast, the cell wall (D), chloroplast (B) and large permanent vacuole (C) are structures unique to plant cells.

(b)(i) Image size; magnification

The actual size of a specimen is found using \( \text{actual size} = \dfrac{\text{image size}}{\text{magnification}} \).
So the two values needed are the measured size of the cell in the image and the magnification of that image.

(b)(ii) vacuole; water; partially permeable; osmosis

The plant cell is placed in pure water, which has a higher water potential than the cell contents.
Water moves into the cell, through the partially permeable cell membrane, causing the vacuole to enlarge and the cell to swell.
This net movement of water molecules down a water potential gradient through a partially permeable membrane is called osmosis.

Question

Fig. 3.1 is a diagram of a palisade cell from a potato plant.
(a)(i) Identify all the structures, labelled in Fig. 3.1, that are also in animal cells.
      (ii) Describe the functions of the cytoplasm and the cell wall.
(b) Aerobic respiration takes place in mitochondria to release energy.
      (i) State the word equation for aerobic respiration.
      (ii) State one use of energy from respiration in living organisms.
(c) A student cuts a small piece of potato.
The student measures the mass of the piece of potato.
The student puts the piece of potato in pure water (water with no chemical impurities).
Describe the effect of the pure water on the mass of the piece of potato.
Include the name of the process in your answer.
(d) Plants are made up of different parts.
Use words from the list to complete the sentence about plants.
organs        tissues        cells        organ systems
Plant leaves are thin, flat …………………… made up of …………………… including phloem and epidermis.

Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):

• Topic B2.1 — Cell structure (Part (a)(i))
• Topic B2.1 — Cell structure (Part (a)(ii))
• Topic B12.1 — Respiration (Part (b))
• Topic B3.2 — Osmosis (Part (c))
• Topic B2.1 — Cell structure (Part (d))

▶️ Answer/Explanation

(a)(i) cell membrane, cytoplasm, mitochondria, nucleus
These structures are found in both plant and animal cells. Chloroplasts, cell walls and large vacuoles are present only in plant cells.

(a)(ii) Cytoplasm: site of metabolic/chemical reactions ; Cell wall: protects/supports the cell
The cytoplasm is where most cellular reactions occur. The cell wall provides structural support and protection, maintaining the shape of the cell.

(b)(i) glucose + oxygen → carbon dioxide + water
Aerobic respiration uses glucose and oxygen to release energy, producing carbon dioxide and water as waste products.

(b)(ii) Protein synthesis / cell division / growth / muscle contraction / passage of nerve impulses / maintenance of constant body temperature / active transport
Energy from respiration is used for many essential life processes including growth, movement and active transport across cell membranes.

(c) Water moves into the potato tissue ; mass increases ; osmosis
Pure water has a higher water potential than the potato cells. Water moves into the potato cells by osmosis through the partially permeable cell membrane, causing the mass to increase.

(d) Plant leaves are thin, flat organs made up of tissues including phloem and epidermis.
Leaves are organs composed of different tissues such as epidermal tissue and vascular tissue (phloem and xylem).

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