Question 5
(a) Robert Hooke and Theodor Schwann are scientists that contributed to the formulation of a Theory.
(i) Name the Theory. [1 mark]
(ii) Explain briefly the contributions of each of the scientists to the formulation of the Theory.
Robert Hooke [3 marks]
Theodor Schwann [2 marks]
(b) A patient’s urine was mixed with Benedict’s solution and the mixture was heated in a test tube. The test was positive.
(i) Use the information to complete the table below.
Test |
Observation |
Inference |
|
|
|
[3 marks]
(ii) Suggest the disease that the patient could be suffering from. [1 mark]
(iii) Name the hormone that its deficiency leads to the disease named in 5(b)(ii).
[1 mark]
(iv) Name the organ in the digestive system that secretes the hormone named in 5(b)(iii). [1 mark]
(c) State two factors each that result in:
(i) increase in population density;
(ii) decrease in population density. [4 marks]
(d) (i) Explain briefly the term primary succession. [3 marks]
(ii) State three examples of primary succession. [3 marks]
(e) State one function each of the following parts of the digestive tract of a grasshopper:
(i) oesophagus;
(ii) stomach;
(iii) intestine;
(iv) anus;
(v) gizzard. [5 marks]
(f) List three structural features that animals use in regulating their body temperature.
[ 3 marks]
Observation
This question was compulsory.
A good number of the candidates performed woeful in the ecological aspects of the question. Majority of them avoided answering questions on primary production and were not able to state examples in line with the requirement of the marking scheme. Candidates answers to listing structural features that animals use in the regulation of body temperature were also at variance with the scorable points.
The expected answers are:
(a)(i) Name of Theory
Cell theory.
(ii) Contributions of scientists to the formulation of Theory
Robert Hooke
- Discovered the cell;
- While using a microscope to examine the cork from a tree bark;
- He observed honeycomb structures/dead cell walls surrounding empty holes;
- Which he called cells.
Theodor Schwann
- Examined bits of different animals under the microscope;
- And observed that all animals are composed of cells;
- He believed that plant and animal cells are similar;
- He said that every living thing is made up of one or more cells.
(b) (i) Table
Test |
Observation |
Inference |
Urine sample + Benedict’s solution + heat |
A brick-red/red colour |
Reducing sugar/glucose |
(ii) Disease that patient is suffering from
Diabetes
(iii) Organ involved in maintaining blood glucose
Pancreas.
(iv) Hormone
Insulin
Note: spelling must be correct to score in (ii) to (iv).
(c) Factors that result in
(i) increase in population density
- Natality/birth rate;
- immigration;
- fecundity/increased fertility;
- abundance/increased food supply;
- decreased death rate/mortality;
- lack of disease epidemic.
(ii) decrease in population density
- Increased death rate/mortality;
- emigration;
- increased rate of disease epidemic/morbidity;
- reduced birth rate/natality;
- decreased food supply/famine;
- competition;
- war;
- natural disaster (only one correct example should score).
(d) (i) Primary succession
Orderly/sequential changes; that occur in plant and animal community; in a given
barren/bare area; over a period of time; until a climax/stable community is established.
(ii) Examples of primary succession
- bare rocks/cliff;
- estuaries;
- abandoned farmlands/pavements;
- shallow lakes/ponds;
- sand dunes;
- barren/bare land left after landslide/volcanic eruption.
(e) Function of parts of the digestive tract of a grasshopper
- Oesophagus
Passage for food materials.
- Stomach
Site for food digestion/production/secretion of digestive enzymes/temporary storage of food.
- Intestine
Site for absorption of nutrients/end product of digestion/absorption of water.
- Anus
Site where undigested foods are expelled/egested.
- Gizzard
Crushes/grinds/mixes food.
(f) Structural features used in regulating body temperature
- skin covered with hair/fur/feather/scales;
- layer of fat under the skin/adipose tissues;
- body size/surface area to volume ratio;
- bare extremities/inner surface of the pinna/ear/sole of feet/tongue of dog.