1. (a) The diagrams below are illustrations of an experiment to demonstrate a biological principle
Study the diagrams carefully and answer the questions that follow
(i) Name the parts labelled I and II
(ii) State two difference between the set-ups A and B
(iii) What is the role played by the part labelled I in the experiment?
(iv) Name the biological principle being demonstrated in this experiment
(v) State one way in which plants benefit from the principle named in (iv)
(vi) State one way in which animals benefit from the principle named in (iv)
ANSWER
1. (a) (i) PART NAME
I – A hollow yam or potato or pawpaw cup or semi-permeable container
II – A beaker or trough
(ii) Differences between set-ups A and B
Set-up A
Set-up B
The sugar solution is concentrated
The sugar solution is dilute
The level of the distilled water is
high
The level of the distilled water is low
The amount of sugar solution is
smaller
The amount of sugar solution is
greater
(iii) Role played by part I
It serves as a semi-permeable membrane – to allow the movement of water molecules from the water into the sugar solution.
(iv) Biological principle demonstrated
Osmosis
(v) How plants benefit from the named principle (osmosis)
• Absorption of water by the roots of plants
• Transportation of water from the roots to the other parts of the plant
• Movement of water from one plant cell to the other
(vi) How animals benefit from osmosis
• Movement of water into the cytoplasm of some organisms such as amoeba
• Re-absorption of water in the kidney tubules of mammals
(b) In an experiment to investigate the reactivity of zinc, a piece of the metal was dropped into a test tube containing dilute hydrochloric acid. The experimental set-up is illustrated below.
Study the set-up carefully and answer the questions that follow.
(i) Write a balanced chemical equation for the reaction that occurred in the experiment.
(ii) Name the gas evolved.
(iii) List two metals which can react in a similar way as the zinc
(iv) List two metals which cannot react in a similar way as the zinc.
(v) Name two glass apparatus which could have been used instead of the test tube.
ANSWER
(b) (i) Balanced equation for the reaction
Zn + 2HCl ⟶ ZnCl2 + H2
(ii) The gas evolved
Hydrogen gas or H2 (gas)
(iii) Metals that can react in a similar way as the zinc
Lithium, Magnesium, Potassium, Sodium, Calcium, Aluminium, Iron
(iv) Metals that cannot react in a similar way as the zinc
Copper, silver, gold, mercury, platinum
(v) Glass apparatus that could have been used.
Beaker, conical flask, measuring cylinder, flat bottomed flask, gas jar
(c) The diagram below is an illustration of a thermos flask
Study the diagram carefully and answer the questions that follow
(i) Name the parts labelled I, II, III, IV and V
(ii) How does the device minimize heat loss or gain through
(α) conduction ? (β) convection ? (ʎ) radiation ?
(iii) State one use of the thermos flask
ANSWER
(c) (i) Parts
I – Cork or plastic/rubber stopper
II – Silvered or shiny surfaced double wall
III – Vacuum or empty space
IV – Cork support or plastic/rubber support
V – Vacuum seal
(ii) How the device minimizes heat loss or gain through
(α) conduction
Minimized by the cork or plastic/rubber stopper and Cork support or
plastic/rubber support
(β) convection
Minimized by the vacuum
(λ) radiation
Minimized by the silvered or shiny surfaced double wall
(iii) Use of the thermos flask
• Maintains the temperature of its contents for a relatively long time, ie, it keeps its hot contents hot and its cold contents cold
• It prevents heat loss or heat gain of its contents for a long period.
(d) The diagrams below illustrate an experimental set-up on a physical property of soil using three soil types, X, Y and Z
Study the set-up carefully and answer the questions that follow:
(i) Name the parts of the set-up labelled I, II, III and IV
(ii) Which of the three soil types has the
(α) highest water holding capacity?
(β) least water holding capacity?
(iii) Name each of the three soil types X, Y and Z
(iv) Suggest a suitable title for the experiment
ANSWER
(d) (i) PARTS
I – funnel
II – cotton wool
III – measuring cylinder
IV – water
(ii) (α) Highest water holding capacity – Z
(β) Least water holding capacity – X
(iii) SOIL TYPES
X – Sandy
Y – Loamy
Z – Clayey
(iv) Suitable title for experiment
• Experiment to compare the water-holding capacities of sandy, loamy and clayey soils
• Experiment to demonstrate the drainage abilities of sandy, loamy and clayey soils.
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