Questions
INSTRUCTIONS TO CANDIDATES
- This paper contains THREE Sections. Answer ALL the questions in the spaces provided IN THIS PAPER.
- ALL the answers must be clear and precise.
- Answer all the questions using correct English.
- You are provided with specimens labeled S and T. Using the appropriate apparatus and reagents provided, use the specimens to answer the questions below.
- Carefully, cut a longitudinal section of specimen S. Draw and label a plain diagram of the cut surface of specimen S. (5 marks)
- State three differences between specimen S and T. (3 marks)
Specimen S Specimen T - Give three functions of the major chemical component in specimen T. (3 marks)
- Which branch of biology deals with the study of the specimens above? (1 mark)
- In which kingdom do the specimen above belong? (1mark)
- Below are photographs of skulls of different mammals, W and X. Study them carefully and use them to answer the questions that follow.
- State the diet of the mammals from which the photographs above were obtained and give a reason in each case. (4 marks)
Diet Reason W X - In a natural set-up, the mammals from which the photographs of skulls W and X were obtained have a biotic interrelationship.
- Identify the biotic interrelationship of such mammals. (1 mark)
- What are the adaptations of the animal with the skull labeled X for efficiency in the named biotic interrelationship in (b) (i) above? (3 marks)
- Draw and label the external structure labeled I on photograph W. (3 marks)
- State the diet of the mammals from which the photographs above were obtained and give a reason in each case. (4 marks)
-
- The photograph below shows the inner surface of the upper left side of the ribcage.
Explain the role of the part labeled M in inhalation. (4 marks) - Below is a photograph of a respiratory system. Study it to answer the questions that follow.
- . Identify the disease. (1 mark)
- Name a chemical compound formed when burning tobacco that accelerates the disease. (1 mark)
- Name a plant excretory product used in the therapy of such a disease. (1 mark)
- Give three ways in which the disease can be treated. (3 marks)
- You are provided with a specimen labeled P. You are also provided with a sharp scalpel, a hand lens, a Petri dish, a glass slide, an iodine solution, and distilled water. Carry out the following procedure and answer the questions that follow.
- Cut off the petiole about 1.5cm from the end where the leaf attaches to the stem.
- Carefully make several thin cross sections through the piece obtained above using a sharp scalpel.
- Put the sections obtained in water in a Petri dish.
- Mount the thinnest section and stain with iodine.
Using a hand lens, observe and then draw a well-labeled diagram of the section observed. (3mks)
- What is the purpose of the following procedures when preparing the sections?
- Making thin cross sections. (1 mark)
- Using a sharp scalpel when cutting thin sections. (1 mark)
- Putting the sections obtained in water. (1 mark)
- The photograph below shows the inner surface of the upper left side of the ribcage.
Confidential
Each student will be required to have the following.
- A sharp scalpel
- A magnifying hand lens
- A mango leaf with a petiole labeled specimen P
- An avocado (preferably ripe) labeled specimen S
- A dry maize grain labeled specimen T
- A Petri-dish
- Distilled water in a wash bottle
- Iodine solution (or access to it)
Marking Scheme
- You are provided with specimens labeled S and T. Using the appropriate apparatus and reagents provided, use the specimens to answer the questions below.
- Carefully, cut a longitudinal section of specimen S. Draw and label a plain diagram of the cut surface of specimen S.
NOTE: For to score the diagram mark; (1x1=1 mark) ⮚ Epicarp and endocarp MUST have a double line otherwise penalize- Mesocarp MUST be bigger than epicarp and endocarp, with endocarp thinnest (proportionality)
- The seeded MUST be indicated within the endocarp
- Drawing is free-hand (not traced using circular objects or using a compass) For labels; (diagram; 1x4=4 marks) ⮚ ARROWS should not be used for labeling
- Outline of ALL structures MUST be solid/continuous
- Any structure should be labeled ONCE, otherwise back-mark and reject both answers. Encourage indication of magnification but DO NOT penalize.
(These rules apply to ALL the Biological drawings)
- State three differences between specimen S and T.
Specimen S Specimen T Epicarp, mesocarp, and endocarp separate Mesocarp fused to epicarp and endocarp (OWTTE) Pericarp is thick Pericarp is thin Fleshy fruit Dry fruit - Give three functions of the major chemical component in specimen T.
- Broken down to release energy in living organisms (e.g. glucose)
- Complex carbohydrates are used to provide mechanical support (e.g. chitin and cellulose)
- Are the stored food in cells (e.g. starch in plants and glycogen in animals) ∙ Excess carbohydrates are converted to fat used for insulation against heat loss. 1x3=3 marks
- Which branch of biology deals with the study of the specimens above?
- Botany 1x1=1 mark
- In which kingdom do the specimen above belong?
- ( Plantae Rej: plantae 1x1=1 mark
- Carefully, cut a longitudinal section of specimen S. Draw and label a plain diagram of the cut surface of specimen S.
- Below are photographs of skulls of different mammals, W and X. Study them carefully and use them to answer the questions that follow.
- State the diet of the mammals from which the photographs above were obtained and give a reason in each case.
Diet Reason W Vegetation/grass/plant (material) Has diastema/lack canines;
Has horny pad/lack upper incisors; ∙ Technical terms well spelled. ∙ Must mention UPPER incisors
(in case the answer is on incisors)X Flesh/Meat
Rej; FreshHas (large/long/curved) sharp pointed/pointed canines
Has carnassial teeth- NB: For BOTH W and X, mark the first reason 1x4=4 marks
- In a natural set-up, the mammals from which the photographs of skulls W and X were obtained have a biotic interrelationship.
- Identify the biotic interrelationship of such mammals.
- Predation
- What are the adaptations of the animal with the skull labeled X for efficiency in the named biotic interrelationship in (b) (i) above?
- The animal has strong jaws to crush bones
- The animal has pointed canines to hold/grasp/tear flesh/prey
- The animal has carnassial teeth to cut and crush bones
- The animal has strong/muscular limbs for fast movement
- The animal has large claws on its forelimbs to hold prey. 1x3=3 marks
- Identify the biotic interrelationship of such mammals.
- Draw and label the external structure labeled I on photograph W
- Diagram mark (D√); 1x1=1 mark Label marks; 2x1=2 marks
- State the diet of the mammals from which the photographs above were obtained and give a reason in each case.
-
- The photograph below shows the inner surface of the upper left side of the ribcage.
Explain the role of the part labeled M in inhalation.- The internal intercostal muscles/M relax; the ribcage moves upwards and outwards; the volume of the ribcage increases while pressure decreases; the air is forced/moves into the lungs; 1x4=4 marks
- Below is a photograph of a respiratory system. Study it to answer the questions that follow.
- Identify the disease
- Lung cancer 1x1=1 mark
- Name a chemical compound formed when burning tobacco that accelerates the disease.
- Tar 1x1=1 mark
- Name a plant excretory product used in the therapy of such a disease.
- Colchicine 1x1=1 mark
- Give three ways in which the disease can be treated.
- Surgery to remove the tumor(s)
- Radiotherapy to destroy cancerous/malignant/carcinogenic cells
- Chemotherapy to destroy cancerous/malignant/carcinogenic cells
- Avoid (active/passive) smoking 3x1=3 marks
- Identify the disease
- You are provided with a specimen labeled P. You are also provided with a sharp scalpel, a hand lens, a Petri dish, a glass slide, an iodine solution, and distilled water. Carry out the following procedure and answer the questions that follow.
- Cut off the petiole about 1.5cm from the end where the leaf attaches to the stem.
- Carefully make several thin cross sections through the piece obtained above using a sharp scalpel.
- Put the sections obtained in water in a Petri dish.
- Mount the thinnest section and stain with iodine.
- Using a hand lens, observe and then draw a well-labeled diagram of the section observed.
- Diagram mark (D√); 1x1=1 mark
Label marks; 2x1=2 marks
- Diagram mark (D√); 1x1=1 mark
- What is the purpose of the following procedures when preparing the sections?
- Making thin cross sections.
- To allow light to pass through (for illumination of parts/cells) 1x1=1 mark
- Using a sharp scalpel when cutting thin sections.
- To avoid destroying tissues/cells/organelles/parts (of the sections) 1x1=1 mark
Rej: To avoid destroying sections
- To avoid destroying tissues/cells/organelles/parts (of the sections) 1x1=1 mark
- Putting the sections obtained in water.
- To keep cells turgid;
- To keep cells alive/not kill the cells/to avoid desiccating cells; 1x1=1 mark Rej: To keep sections alive (OWTTE) without mentioning tissues, cells, organelles, or parts.
- Making thin cross sections.
- The photograph below shows the inner surface of the upper left side of the ribcage.
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