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DSF 4 Biology P530 2

This document provides instructions for a biology exam consisting of two sections - Section A with one question divided into 5 parts, and Section B with 6 questions from which students must answer 3. Section A's question is on a study that measured isoprene emissions and photosynthesis in black poplar plants under drought conditions and increased temperatures. Section B questions cover a range of biology topics including feedback in biological systems, effects of light on plants, enzyme activity, air and land pollution, and evidence for the theory of evolution. Students are advised to plan their answers carefully and include diagrams where needed.

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Mwesigwa Hannah
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68 views3 pages

DSF 4 Biology P530 2

This document provides instructions for a biology exam consisting of two sections - Section A with one question divided into 5 parts, and Section B with 6 questions from which students must answer 3. Section A's question is on a study that measured isoprene emissions and photosynthesis in black poplar plants under drought conditions and increased temperatures. Section B questions cover a range of biology topics including feedback in biological systems, effects of light on plants, enzyme activity, air and land pollution, and evidence for the theory of evolution. Students are advised to plan their answers carefully and include diagrams where needed.

Uploaded by

Mwesigwa Hannah
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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October 2023 Dongo-Shema F.

+256 782 642 338 Release: 4; Version: National

P530/2
BIOLOGY
Paper 2
October 2023
2½ hours

DONGO-SHEMA F. PAPERS
Release: ①②③❹⑤⑥⑦⑧⑨⑩⑪⑫⑬⑭⑮⑯⑰⑱⑲⑳
Version: School  National  Seminar  Textbook 

UNMATCHED!
In Form & Substance
Paper 2

2 hours 30 minutes

INSTRUCTIONS:

This paper consists of sections A and B.

Answer question one in section A plus three questions from section B.

Candidates are advised to read the questions carefully, organize their answers and present
them precisely and logically, illustrating with well labelled diagrams where necessary.
October 2023 Dongo-Shema F. +256 782 642 338 Release: 4; Version: National

SECTION A: (40 MARKS)


1. Isoprene is a chemical synthesized and emitted in large amounts by some plant species,
especially oak (Quercus sp) and poplar (Populus sp.) trees. Black poplar (Populus
nigra) plants were subjected to two raised temperatures and to drought. Measurements
of photosynthesis and isoprene emission were made during a 35-day-long drought
stress (drought period) and a 3 and 15 days after re-watering stressed plants (recovery
period). The rate of photosynthesis was recorded as the carbon dioxide taken up per
unit of leaf area per second.

(a) Describe the following during the drought and recovery periods at 25 0C:
(i) Isoprene emissions. (05 marks)
(ii) Rate of photosynthesis. (03 marks)
(b) Compare the effect of both heat treatments on the emission of isoprene. (06 marks)
(c) Explain the effect of the following on the rate of photosynthesis:
(i) Drought and re-watering. (10 marks)
(ii) Heat treatment. (10 marks)
(d) Suggest reasons for some plant species synthesizing and emitting isoprene, but not
other plant species. (04 marks)
(e) Suggest other methods by which the rate of photosynthesis could have been measured
in this experiment. (02 marks)
October 2023 Dongo-Shema F. +256 782 642 338 Release: 4; Version: National

SECTION B: (40 MARKS)

2. (a) Compare positive and negative feedback in biological systems. (08 marks)
(b) Describe the role of positive feedback during childbirth. (12 marks)

3. (a) What are the effects of light intensity on plant growth and development?
(10 marks)
(b) Describe the physiological mechanisms by which plants perceive and respond
to light stimuli. (10 marks)

4. (a) Explain how the concept of inhibition affects enzyme activity. (11 marks)
(b) How do enzymes facilitate the movement of substances across the
cell membrane? (09 marks)

5. (a) Explain the sources and types of air pollution. (13 marks)
(b) What are the effects of land pollution on agricultural productivity?
(07 marks)
6. (a) Describe the theory of evolution by natural selection. (10 marks)
(b) Explain the evidence for natural selection. (10 marks)

END.

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