CSEE
Biology · Paper 1 · 2021
43 questions 🇹🇿 NECTA ✓ Official NECTA answers
CSEE
🇹🇿 NECTA
✓ Official NECTA answers
Biology · Paper 1 · 2021
43 questions
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200 TZS
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Questions (43)
Section A
3.
5 marks
Outline the procedures for collecting and preserving insects.
(a)
Describe the collection methods.
2 mk
(i)
Where do wild birds usually live?
1 mk
(none)
List at least five key issues to consider while dissecting animals.
5 mk
(i)
Use forceps to cut and make a small opening between the two sepals, then use hand to peel the calyx completely from the flower.
0 mk
(a)
For the weighing scales such as digital and triple beam balance to measure accurate mass, state one preparation that should be observed for each.
2 mk
(b)
Explain how to anesthetize insects.
1 mk
(ii)
What is used to capture wild birds?
1 mk
(ii)
Detach the petals by pulling each one downwards towards the receptacle until the entire corolla is removed from the flower.
0 mk
(b)
Mention one preparation for the ruler and tape measure.
1 mk
(iii)
Detach the filament and use the hand lens to observe anther and filament.
0 mk
(iii)
How are dead bird specimens preserved?
1 mk
(c)
State the common measures in Biology.
3 mk
(c)
Detail the preservation method for insects.
2 mk
(d)
Name the instrument used to measure temperature.
1 mk
(d)
Set the microscope for observation.
0 mk
(e)
What is the function of glycerol in step (ix)?
1 mk
(e)
What is used to measure pulse rate?
1 mk
(f)
Why should air bubbles be avoided when putting on the coverslip?
2 mk
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4.
1 mark
Refer to the table above. Which of the following topics are assessed in ACSEE only?
A.
Nervous coordination in mammals and Reproduction in mammals
B.
Nervous coordination in mammals and Phylum arthropoda
C.
Meiosis and Gaseous exchange in mammals
D.
Dissection of small animals and Plant sections
5.
1 mark
Refer to the table above. Which of the following topics are assessed in DSEE only?
A.
Nervous coordination in human and Meiosis
B.
Preparation of common Biology chemicals and reagents and Dissection of small animals
C.
Phylum arthropoda and Phylum chordata
D.
Movement of human body and Taxonomic keys
6.
1 mark
Refer to the table above. Which of the following topics are assessed in both ACSEE and DSEE?
A.
Nervous coordination in human and Nervous coordination in mammals
B.
Dissection of small animals and Plant sections
C.
Meiosis and Properties of food substances
D.
Reproduction in mammals and Gaseous exchange in mammals
8.
1 mark
Refer to the table above. Which of the following topics are assessed in CSEE and DSEE but not in ACSEE?
A.
Nervous coordination in human and Meiosis
B.
Preparation of common Biology chemicals and reagents and Dissection of small animals
C.
Phylum arthropoda and Phylum chordata
D.
Movement of human body and Taxonomic keys
9.
1 mark
Refer to the table above. Which of the following topics are assessed in ACSEE and DSEE but not in CSEE?
A.
Nervous coordination in human and Meiosis
B.
Nervous coordination in mammals and Phylum arthropoda
C.
Preparation of common Biology chemicals and reagents and Dissection of small animals
D.
Properties of food substances and Organic constituents of cell
10.
1 mark
Refer to the table above. Which of the following topics are assessed in CSEE only?
A.
Nervous coordination in human, Meiosis and Reproduction in mammals
B.
Properties of food substances, Organic constituents of cell and Factors affecting rate of photosynthesis
C.
Nervous coordination in mammals and Phylum arthropoda
D.
Preparation of common Biology chemicals and reagents and Dissection of small animals
Section B
2.
10 marks
Dissection involves the displaying of various systems of plants and animals. It is expected that, teachers and laboratory technicians should be able to prepare and dissect animals and flowers for Biology practical examinations. They should also be able to conduct assessment of candidates’ dissections and drawings. Key Issues to Consider While Dissecting the Animals Teachers and laboratory technicians should be able to do the following:
(1)
What are the safety precautions that should be taken when preparing dilute hydrochloric acid?
2 mk
(none)
Place the microscope away from the edge of the table and rotate the objective to bring it in line with the body tube until you hear a faint clicking sound.
Look through the eye lens and adjust the mirror below to attain a good illumination of the circular area visible.
Keep the slide to be studied on the stage such that, the specimen lies just above the aperture of the stage and hold it in position by the help of the clips. The slide, the stage, and the lens should be clean.
5 mk
(i)
Use forceps to cut and make a small opening between the two sepals, then use hand to peel the calyx completely from the flower.
0 mk
(a)
Mention two habitats where ferns can be found.
1 mk
(i)
State two places where reptiles can be collected.
2 mk
(e)
Outline the safety precautions that should be taken when preparing dilute hydrochloric acid.
3 mk
(a)
Prepare the dissecting tray.
2 mk
(2)
The molar mass of HCl is 36.5 g/mol. If a concentrated HCl solution has a density of 1.18 g/cm³ and is 37% pure, calculate its molarity.
3 mk
(ii)
Detach the petals by pulling each one downwards towards the receptacle until the entire corolla is removed from the flower.
0 mk
(b)
Identify one example of a monocotyledon and one example of a dicotyledon.
2 mk
(ii)
Name three methods that can be used to collect reptiles.
3 mk
(b)
Prepare specimen for dissection.
3 mk
(3)
If you need to prepare 500 ml of 1 M HCl solution from a stock solution of 12 M HCl, what volume of the stock solution is required?
2 mk
(iii)
Use forceps to cut and make a small opening at the base of the staminal tube, then expose the ovary with your finger nails by pilling off the staminal tube of the flower around the ovary.
0 mk
(c)
Outline the steps to prepare seedlings from seeds.
2 mk
(c)
Dissect the animals/flowers to display various systems for candidates to observe.
5 mk
(iv)
Use needle to cut at the base of the staminal tube, then extend the incision to the base of the stigma. Care must be taken not to damage the ovary and the style under it.
0 mk
(4)
Describe the correct procedure for diluting concentrated hydrochloric acid.
3 mk
(d)
Remove the leaf from the water and insert it in a test tube containing less than half-filled ethanol.
0 mk
(d)
Describe how to preserve flowers for some days.
1 mk
(e)
Plug the test tube with a piece of cotton wool.
0 mk
(v)
Repeat the cuttings as much as possible, and then pull apart the strands to completely remove the staminal tube from the flower.
0 mk
(vi)
Look at the flower you will see stigma, style and ovary collectively known as the carpel.
0 mk
(vii)
Observe the ovary, stigma, and style of your flower with a magnifying glass.
0 mk
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Section C
0.
0 marks
Dissection of a Flower Identify the relevant flower by assessing the floral parts and location of the following in the whole flower:
(i)
Place the frog on the dissecting tray.
0 mk
(a)
Which type of food source can be used to prepare lipid solution?
2 mk
(ii)
Turn the frog on its back and pin down the legs.
0 mk
(b)
What is the concentration of the lipid solution prepared?
1 mk
(ix)
Cover the dissected specimen completely with water to make clear observation.
0 mk
(iii)
Look for the opening to the specimen’s cloaca, located between the hind legs. Use forceps to lift the skin and use scissors to cut along the centre of the body from the cloaca to the lip.
0 mk
(x)
With the help of a hand lens, observe the dissected specimen and note the position and shape of the organs and systems.
0 mk
(none)
petals that form a corolla;
0 mk
(iv)
Turn back the skin, cut towards the side at each leg and pin the skin flat.
0 mk
(v)
Ligature the ventral abdominal vein at two sides using thread in order to prevent bleeding. Then, cut between the ligatured points.
0 mk
(xi)
Carefully remove unwanted organs and tissues to expose targeted organs or systems as per instructions.
0 mk
(vi)
Using forceps lift the abdominal vein and cut alongside it to the breast bone to open up the body cavity and make insicions towards the limbs. Pin the inner skin.
0 mk
(vii)
Cover the frog completely with water for clear observation.
0 mk
((viii)
With the help of a hand lens, observe the dissected frog and note the position and shape of the organs and the system. You may use forceps to remove the unwanted organs to facilitate observation of the organ under investigation as per 3 Hours Practical Advance Instructions.
0 mk
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Section D
1.
8 marks
The table below shows the collection and preservation methods for different animal groups. | Animal Group | Collection Method | Preservation Method | |---|---|---| | Amphibians | (i) _________________________ | (i) Inject with 10-30% formaldehyde. | | | (ii) Sweep nets | (ii) _________________________ | | Reptiles | Sweep nets, traps or fishing nets | (i) 10% formaldehyde solution in air tight container. | | | Rocks or caves | (ii) _________________________ | | Birds | Bird trap nets | (i) 10% formaldehyde solution in air tight container. | | | (i) _________________________ | (ii) _________________________ | | Mammals | Trap (overnight) | (i) 10% formaldehyde solution. | | | Sweep net (during day) | (ii) _________________________ | | Animal Parts | Feathers, beak, skin, bones, teeth | Preserved in 10% formaldehyde solution. |
| Animal Group | Collection Method | Preservation Method |
|---|---|---|
| Amphibians | (i) _________________________ | (i) Inject with 10-30% formaldehyde. |
| (ii) Sweep nets | (ii) _________________________ | |
| Reptiles | Sweep nets, traps or fishing nets | (i) 10% formaldehyde solution in air tight container. |
| Rocks or caves | (ii) _________________________ | |
| Birds | Bird trap nets | (i) 10% formaldehyde solution in air tight container. |
| (i) _________________________ | (ii) _________________________ | |
| Mammals | Trap (overnight) | (i) 10% formaldehyde solution. |
| Sweep net (during day) | (ii) _________________________ | |
| Animal Parts | Feathers, beak, skin, bones, teeth | Preserved in 10% formaldehyde solution. |
(a)
Fill in the missing information in the table.
8 mk
(a)
Preparation of the Dissecting Tray
0 mk
(i)
State two places where amphibians can be found.
2 mk
(1)
State two requirements for preparing a solution of a specific molarity from a concentrated liquid.
2 mk
(ii)
What is the best time to collect toads?
1 mk
(2)
Calculate the molarity of a stock solution given the following information: % assay = 99.9%, density (ρ) = 1.16 g/cm3, and molar mass (Mr) = 36.46 g/mol.
3 mk
(a(i))
Heat some paraffin-wax to melting point.
0 mk
(3)
Using the dilution formula M₁V₁ = M₂V₂, calculate the volume of concentrated hydrochloric acid (31.78 M) needed to prepare 1000 ml of 1 M dilute HCl.
3 mk
(iii)
State the method used to capture amphibians.
1 mk
(c)
Why is the leaf dipped in warm water after boiling in ethanol?
1 mk
(c)
Explain the purpose of warming the ethyl alcohol in step (i) of Sudan III solution preparation.
0 mk
(a(ii))
Pour the wax in the dissecting tray.
0 mk
((a)(i)
Which parts are male reproductive parts and female reproductive parts?
2 mk
(a(iii)
Leave the wax to cool. The cooling process may be hastened by immersing the dissecting tray in cold water.
0 mk
(d)
What is the expected observation when iodine solution is added to a leaf containing starch?
1 mk
(4)
Refer to Table 2. What is the volume of concentrated acid required to prepare 1 litre of 1M HCl solution if its density is 1.18 g/cm3 and purity is 85.9%?
2 mk
(note:)
It takes time to get homogeneous solution, so keep on stirring.
0 mk
(iv)
How are dead specimens of amphibians preserved?
1 mk
(b)
Preparation of Animal Specimen for Dissection
0 mk
(e)
What does the observation in the variegated leaf indicate?
1 mk
(e)
Explain the note: 'add acid to water and not water to acid.'
0 mk
(5)
List the chemical requirements for the preparation of Sudan III solution.
2 mk
((a)(v)
Name the part that develops into a fruit and the part that develops into a seed.
2 mk
(b(i))
wet the cotton wool with chloroform and put it inside an air tight container;
0 mk
(f)
Outline the general procedures for collecting, preparing, and preserving plant specimens.
4 mk
(6)
Describe the procedure for preparing 100 ml of Sudan III solution. Include the steps for making 95% ethyl alcohol if 100% pure alcohol is available.
3 mk
(b)
The following are structures found in a flower, list them according to the order they are observed in the diagram:
Stigma, petal, sepal, ovary, stamen, filament, anther, style.
8 mk
(b(ii))
put a live animal in the air tight container containing the wet cotton wool;
0 mk
(b(iii)
leave the animal in the air tight container for about 4 minutes to make it unconscious;
0 mk
(b(iv))
remove the animal from the air tight container by using forceps and place it in the dissecting tray; and
0 mk
(b(v))
leave the specimen for few minutes to allow evaporation of chloroform.
0 mk
((c)(i)
State three agents of pollination.
3 mk
(3.4.2)
Dissection of Rat/Mouse and Guinea Pigs
The following apparatuses, specimens and materials are required for dissection:
Dissecting kit/instruments, hand lens, scalpel, microscope, needle, forceps, surgical blade,
slide, fresh flowers, water, fresh rats/mouse/guinea pigs, fresh frog/toad, T-pins, pieces of
cotton wool and cotton thread.
0 mk
(d)
Explain the process of fertilization in flowering plants.
5 mk
(iii)
Boil the mixture while stirring to obtain a homogenous solution.
0 mk
(iv)
Leave the solution to cool at room temperature.
0 mk
(proce)
Pin the folds of skin by placing one pin above the fore limbs, below the fore limbs and another one near the hind limbs on both sides.
0 mk
(i)
Dissolve about 10 ml of vegetable oil in a litre of distilled, rain or tap water to obtain 1% lipid mixture.
0 mk
(ii)
Stir the mixture gently.
0 mk
(none)
Apart from other fitting of the laboratory, the following are required;
0 mk
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