THE UNITED REPUBLIC OF TANZANIA

NATIONAL EXAMINATIONS COUNCIL OF TANZANIA

ADVANCED CERTIFICATE OF SECONDARY EDUCATION EXAMINATION

BIOLOGY 1

1. This paper consists of sections A and B with a total of ten (10) questions.
2. Answer all questions in section A and two (2) questions from section B.
3. Section A carries seventy (70) marks and section B carries thirty (30) marks.
4. All writing must be in blue or black ink, except drawings which must be in pencil.
5. Communication devices and any unauthorised materials are not allowed in the examination room.
6. Write your Examination Number on every page of your answer booklet(s).

Section A (70 Marks)

1. (a) Briefly explain how each of the following features of a chloroplast helps in trapping light energy and producing carbohydrates: (i) Thylakoid membranes (2 marks) (ii) Stroma (2 marks) (iii) Chlorophyll pigments (1 mark) (b) State two importance of each of the following organelles: (i) Endoplasmic Reticulum (2 marks) (ii) Peroxisomes (2 marks) (iii) Centrioles (1 mark)
2. (a) Analyse five differences between plant cells and animal cells. (5 marks) (b) Using two points, justify the need for prokaryotic cells to have a cell wall. (5 marks)
3. (a) Study the structure of the molecule shown in the given figure and answer the questions that follow:
   $\text{R-CH(NH}_2\text{)-COOH}$
   (i) Identify the molecule. (1 mark) (ii) Explain three ways in which the molecule is important in human body. (6 marks) (b) Analyse three features that are shared by xylem and phloem in plants. (3 marks)
4. Draw well labelled diagrams to show the arrangement of a reflex arc from a sensory receptor to an effector. (10 marks)
5. Differentiate mitosis from meiosis based on the following aspects: (a) Specific site of occurrence (2 marks) (b) Number of cells formed (2 marks) (c) Result of cytoplasmic division during anaphase I and anaphase II (2 marks) (d) Genetic content of daughter cells (2 marks) (e) Role in organisms (2 marks)
6. With the help of a diagram, explain how two molecules of a 3 carbon compound are converted to a 6 carbon compound during gluconeogenesis. (10 marks)
7. (a) Evaluate the rate of photosynthesis based on each of the following criteria: (i) Light intensity (2 marks) (ii) Carbon dioxide concentration (2 marks) (iii) Temperature (2 marks) (iv) Water availability (2 marks) (b) Justify the fact that when the same amount of protein and carbohydrate are consumed, protein is generally not used for energy generation in preference to carbohydrates. (2 marks)

Section B (30 Marks)

1. Enzymes play a vital role in all biochemical reactions in living organisms. Evaluate four benefits of enzyme specificity and three factors that affect enzyme activity. (15 marks)
2. In four points, justify the fact that "decomposers are essential for the sustenance of life on Earth". (15 marks)
3. With the aid of a diagram, describe the life cycle of a flowering plant (Angiosperm). (15 marks)