Download EXERCISE Objectives Select the best answer to each question: 1

EXERCISE
Objectives
Select the best answer to each question:
1. Which one of the following is not an excretory product?
A. Carbon dioxide
B. Water
C. Faeces
D. Nitrogenous waste
2. Which of the following parts of a plant do not store excretory products?
A. Buds
B. Roots
C. Stems
D. Bark
3. A number of waste products of plants may be found in the following
A. Fruits, leaves and roots
B. Bark, flowers and Guard cells
C. Ovary, pollen tubes and ovules
D. Embryo sac, endosperm and ovary
4. Plants do not have specialized excretory organs like those of animals because:
A. Much of their waste passes out in solution into the soil
B. Much of their waste passes out in gaseous and non-toxic forms
C. Plants do not take in many chemicals which they do not need
D. Plants do not excrete waste products
5.
The part of the flowering plants which carries out the main function of excretion of gaseous waste
products is the:
A. Shoot system
B. Root system
C. Leaves
D. Flowers
6. Which of the following is a waste product of plants?
A. Urea
B.
Carbon dioxide
C.
Uric acid
D. Ammonia
7. Which of the following waste products from plants is dangerous to humans?
A. Rubber
B.
Colchicine
C.
Nicotine
D. Quinine
8. Which of the following waste products may be considered very useful to humans?
A. Nicotine
B.
Papain
C.
Cocaine
D. Cannabis
Short answer questions
6a) What is excretion?
b) Name the products excreted by
i)
flowering plants
ii)
mammals
c) Name at least 4 useful waste products and 4 harmful / dangerous waste products of
plants.
Essay question
7a) Describe an experiment to show that plants give off carbon dioxide, despite the fact
dioxide is utilized by plants in the process of photosynthesis.
that carbon
b) Why don’t plants possess special excretory organs like the animals?
Answers
Objectives
1.C
2. A
3. A
4. B
5. C
6. B
7. C
8. B
Short answer questions
6 a) Excretion is the removal of waste products of metabolism from the cells of living organisms.
b) (i) Oxygen, water vapour and carbon dioxide
(ii) Carbon dioxide, nitrogenous waste e.g. urea
c) Quinine, colchicines, rubber (latex), oxygen and papain are useful waste products.
However, Nicotine, cannabis, miraa, cocaine and caffeine are harmful wastes.
Essay
7a) An experiment to show that plants give off carbon dioxide:
Requirements
-
Bromothymol blue indicator
Boiling tubes (2)
Aluminium foil paper
Cork
Elodea plant or spirogyra
Procedure
1.
2.
3.
4.
5.
Obtain elodea plants or filaments of spirogyra from a pond.
Put bromothymol blue in a boling tube, which has been covered with aluminium foil place the
plant into the indicator
Set up control, i.e. the indicator in a boiling tube but without a plant.
Keep the apparatus on the side bench for about 3 hours.
Note and explain the observations made.
Apparatus
The experiment is set up as shown in the diagram above. It is important to set up a control as well.
Hydrogen carbonate indicator gives equally good results, if bromothymol blue is not available.
7b) Plants do not possess special excretory organs like the animals because:
Most of plants’ wastes are gaseous and are lost by diffusion through stomata.

The waste product, oxygen is utilized as a fuel in respiration, while carbon dioxide is used as a
raw material in photosynthesis.

There is very little accumulation of toxic wastes e.g. nitrogenous wastes.

The main waste products are formed slowly from breakdown of carbohydrates, hence low rate at
which wastes are formed.
A number of wastes are stored in a non-toxic form
