WAEC SSCE - Biology - 2008 (Practical)
Frage 1 Bericht
Study carerully Specimens H, J, Kand L and use them to answer the following question:
(a) Make a drawing 8-10cm long of the longitudinal section of specimen H and label fully.
(ii) What type of fruit is specimen H?
(ii) State two other examples of the type of fruit to wnich specimen H belongs.
(iv) Is specimen H a true fruit or a false fruit?
(v) Give one reason for your answer in a(iv) above.
(vi) State the food classes present in specimen H.
(b)(i) State one(1) feature common to specimens J, K and L.
(ii) State two observable characteristic features each of specimens J, K and L.
(iii) State the mode of vegetative propagation of specimens K and L.
(C) State the biological significance of specimens K.
(a)(i) Drawing of the longitudinal section of Specimen H (tomato)
A well-proportioned biological drawing of the L.S. of the tomato, 8–10 cm long, drawn in clean sharp pencil lines with no shading and with all label lines horizontal and non-crossing, is shown below.
The drawing shows the outer pericarp (fruit wall) made up of the thin epicarp (skin), the fleshy mesocarp and the inner endocarp; the locules (chambers) filled with juicy pulp; the fleshy placenta from which the seeds arise; the numerous seeds embedded in the pulp; and the fruit-stalk scar at the point of attachment.
(a)(ii) Type of fruit
Specimen H is a berry.
(a)(iii) Two other examples of the same type of fruit
Pawpaw and orange (other acceptable examples: guava, pepper, garden egg).
(a)(iv) True or false fruit
Specimen H is a true fruit.
(a)(v) Reason
It develops entirely from the fertilised ovary of the flower, with no other floral part contributing to the fleshy edible portion.
(a)(vi) Food classes present in Specimen H (tomato)
Vitamins, mineral salts, carbohydrates (sugars) and water.
(b)(i) One feature common to Specimens J, K and L
They are all leaves (or are modified leaves / leaf structures).
(b)(ii) Two observable characteristic features of each
J (Gloriosa leaf): the tip of the midrib is drawn out into a tendril; the leaf is sessile (no petiole) and has parallel veins.
K (Bryophyllum leaf): the leaf is succulent / fleshy with a waxy surface; it bears buds (plantlets) at the notches along its margin.
L (onion bulb): it has swollen fleshy leaf-bases that store reserve food and a stem reduced to a disc-like structure bearing terminal and axillary buds, protective scale leaves and adventitious roots.
(b)(iii) Mode of vegetative propagation of Specimens K and L
K (Bryophyllum): adventitious buds sprout at the notches on the leaf margin and grow into new plantlets that drop off and root.
L (onion bulb): terminal and lateral (axillary) buds sprout to form new aerial shoots and daughter bulbs.
(c) Biological significance of Specimen K (Bryophyllum)
It carries out vegetative reproduction, producing new plants that preserve the characteristics of the parent plant; the succulent leaf acts as a storage organ for water and mineral salts and can also carry out photosynthesis.
Antwortdetails
(a)(i) Drawing of the longitudinal section of Specimen H (tomato)
A well-proportioned biological drawing of the L.S. of the tomato, 8–10 cm long, drawn in clean sharp pencil lines with no shading and with all label lines horizontal and non-crossing, is shown below.
The drawing shows the outer pericarp (fruit wall) made up of the thin epicarp (skin), the fleshy mesocarp and the inner endocarp; the locules (chambers) filled with juicy pulp; the fleshy placenta from which the seeds arise; the numerous seeds embedded in the pulp; and the fruit-stalk scar at the point of attachment.
(a)(ii) Type of fruit
Specimen H is a berry.
(a)(iii) Two other examples of the same type of fruit
Pawpaw and orange (other acceptable examples: guava, pepper, garden egg).
(a)(iv) True or false fruit
Specimen H is a true fruit.
(a)(v) Reason
It develops entirely from the fertilised ovary of the flower, with no other floral part contributing to the fleshy edible portion.
(a)(vi) Food classes present in Specimen H (tomato)
Vitamins, mineral salts, carbohydrates (sugars) and water.
(b)(i) One feature common to Specimens J, K and L
They are all leaves (or are modified leaves / leaf structures).
(b)(ii) Two observable characteristic features of each
J (Gloriosa leaf): the tip of the midrib is drawn out into a tendril; the leaf is sessile (no petiole) and has parallel veins.
K (Bryophyllum leaf): the leaf is succulent / fleshy with a waxy surface; it bears buds (plantlets) at the notches along its margin.
L (onion bulb): it has swollen fleshy leaf-bases that store reserve food and a stem reduced to a disc-like structure bearing terminal and axillary buds, protective scale leaves and adventitious roots.
(b)(iii) Mode of vegetative propagation of Specimens K and L
K (Bryophyllum): adventitious buds sprout at the notches on the leaf margin and grow into new plantlets that drop off and root.
L (onion bulb): terminal and lateral (axillary) buds sprout to form new aerial shoots and daughter bulbs.
(c) Biological significance of Specimen K (Bryophyllum)
It carries out vegetative reproduction, producing new plants that preserve the characteristics of the parent plant; the succulent leaf acts as a storage organ for water and mineral salts and can also carry out photosynthesis.
Frage 2 Bericht
(a)(i) Specimen A is a flower. Remove all the stamens and three petals from specimen A leaving the special petal.
Make a drawing 10-12cm long of the remaining parts of specimen A and label fully.
(ii) what type of ovary is present in specimen A?
(ii) Give one reason for your answer in 1(a) (i) above.
(iv) Describe the petals and sepals of specimen A.
(v) What is the function of the special petal?
(vi) State three features of specimen A which have led to the success of flowering plants.
(b)(i) What type of fruit is specimen B?
(ii) Give two other examples of the fruit type.
(iil) State the mode of dispersal of specimen B.
(iv) State two biological importance of the class of fruit to which specimen B belongs.
(a)(i) Drawing of the remaining parts of Specimen A
After removing all the stamens and three of the petals from the papilionaceous flower (Specimen A) and leaving only the special (standard) petal, the remaining parts are the calyx, the single standard petal, the gynoecium (ovary, style and stigma) borne on the receptacle, and the flower stalk. A drawing 10 to 12 cm long of these parts, fully labelled, is shown below.
(a)(ii) Type of ovary
Superior ovary.
(a)(iii) Reason
The ovary is located at a higher position than the receptacle; that is, it sits on top of the receptacle, above the point of attachment of the other floral parts (the sepals and petals).
(a)(iv) Description of the petals and sepals of Specimen A
- The sepals are of the same colour as the petals (petaloid) and are smaller than the petals in size.
- One of the sepals is keel-shaped.
- The petals are fan-shaped and brightly coloured.
- The special (standard) petal is tubular and flat, bearing guide marks.
(a)(v) Function of the special petal
The large, brightly coloured standard petal guides the visiting insect (bee) to the nectar, acting as an advertisement and landing platform that promotes cross-pollination.
(a)(vi) Three features of Specimen A responsible for the success of flowering plants
- Brightly coloured petals which attract insects that pollinate the flower.
- Large petals which are easily seen by the pollinating insects.
- Presence of nectar which attracts insects and enhances cross-pollination, leading to variation and survival of the species.
(Sticky stigma to hold pollen grains, and sticky, rough pollen grains that attach to insects, are further pollination-ensuring features.)
(b)(i) Type of fruit (Specimen B)
A legume (pod).
(b)(ii) Two other examples of the fruit type
Bean and pea (others include Crotalaria, Caesalpinia, Delonix sp. and Mucuna).
(b)(iii) Mode of dispersal of Specimen B
By an explosive (self) mechanism, in which the dry pod splits open suddenly along its two sutures and flings out the seeds.
(b)(iv) Two biological importances of legumes
- They are a source of food and protein (and feed for livestock).
- They fix nitrogen in their root nodules, enriching the soil (they also serve as cover crops that check erosion).
Antwortdetails
(a)(i) Drawing of the remaining parts of Specimen A
After removing all the stamens and three of the petals from the papilionaceous flower (Specimen A) and leaving only the special (standard) petal, the remaining parts are the calyx, the single standard petal, the gynoecium (ovary, style and stigma) borne on the receptacle, and the flower stalk. A drawing 10 to 12 cm long of these parts, fully labelled, is shown below.
(a)(ii) Type of ovary
Superior ovary.
(a)(iii) Reason
The ovary is located at a higher position than the receptacle; that is, it sits on top of the receptacle, above the point of attachment of the other floral parts (the sepals and petals).
(a)(iv) Description of the petals and sepals of Specimen A
- The sepals are of the same colour as the petals (petaloid) and are smaller than the petals in size.
- One of the sepals is keel-shaped.
- The petals are fan-shaped and brightly coloured.
- The special (standard) petal is tubular and flat, bearing guide marks.
(a)(v) Function of the special petal
The large, brightly coloured standard petal guides the visiting insect (bee) to the nectar, acting as an advertisement and landing platform that promotes cross-pollination.
(a)(vi) Three features of Specimen A responsible for the success of flowering plants
- Brightly coloured petals which attract insects that pollinate the flower.
- Large petals which are easily seen by the pollinating insects.
- Presence of nectar which attracts insects and enhances cross-pollination, leading to variation and survival of the species.
(Sticky stigma to hold pollen grains, and sticky, rough pollen grains that attach to insects, are further pollination-ensuring features.)
(b)(i) Type of fruit (Specimen B)
A legume (pod).
(b)(ii) Two other examples of the fruit type
Bean and pea (others include Crotalaria, Caesalpinia, Delonix sp. and Mucuna).
(b)(iii) Mode of dispersal of Specimen B
By an explosive (self) mechanism, in which the dry pod splits open suddenly along its two sutures and flings out the seeds.
(b)(iv) Two biological importances of legumes
- They are a source of food and protein (and feed for livestock).
- They fix nitrogen in their root nodules, enriching the soil (they also serve as cover crops that check erosion).
Frage 3 Bericht
observe specimen C carefully and answer the following questions.
(a)(i) State tne class to which specimen C belongs.
(ii) Give three reasons for placing Specimen C in that class.
(iii)State two food items which specimen C feeds on.
(b) State two observation of each of specimen C which adapt it to: (i) its mode of feeding (ii) locomotion
(c) List three observable characters of specimen C which can be inherited.
(ii) If white feather colour (W) Is dominant in chickens over black feather colour (w),
with the aid of qenetic.diagrams show how it can be determined whether specimen C is homozygous dominant or heterozygous dominant.
(a)(i) Class of specimen C
Specimen C (a cock) belongs to the class Aves (birds).
(a)(ii) Three reasons for placing it in that class
- Its body is covered with feathers.
- Its fore-limbs are modified into wings.
- Its mouth is modified into a horny beak without teeth. (It also has scaly legs and lays hard-shelled eggs.)
(a)(iii) Two food items it feeds on
Grains (seeds) and insects. (It also takes worms and green vegetables.)
(b)(i) Two adaptations for its mode of feeding
- A short, strong, horny beak for pecking and picking up grains and insects.
- Strong, sharp claws on the toes for scratching the surface of the ground in search of food.
(b)(ii) Two adaptations for locomotion
- Fore-limbs modified into wings for flying, with a streamlined body that reduces air resistance.
- Strong, clawed hind limbs for walking, running and scratching, and tail feathers for steering and balancing.
(c)(i) Three observable inheritable characters
Colour of feathers, shape of comb and colour of the wattle. (Size of comb, shape of beak and body size are also acceptable.)
(c)(ii) Test cross to determine whether specimen C is homozygous or heterozygous dominant
White feather colour (W) is dominant over black (w). A white cock may be homozygous (WW) or heterozygous (Ww). To find out, carry out a test cross by mating it with a homozygous recessive black fowl (ww).
Case 1: if specimen C is WW
Parents: WW (white) \( \times \) ww (black)
Gametes: all W \( \times \) all w
Offspring: all Ww - every chick is white.
Case 2: if specimen C is Ww
Parents: Ww (white) \( \times \) ww (black)
Gametes: W and w \( \times \) all w
Offspring: Ww (white) and ww (black) in the ratio 1 white : 1 black.
Conclusion: If all the offspring are white, specimen C is homozygous dominant (WW). If about half of the offspring are black, specimen C is heterozygous dominant (Ww).
Antwortdetails
(a)(i) Class of specimen C
Specimen C (a cock) belongs to the class Aves (birds).
(a)(ii) Three reasons for placing it in that class
- Its body is covered with feathers.
- Its fore-limbs are modified into wings.
- Its mouth is modified into a horny beak without teeth. (It also has scaly legs and lays hard-shelled eggs.)
(a)(iii) Two food items it feeds on
Grains (seeds) and insects. (It also takes worms and green vegetables.)
(b)(i) Two adaptations for its mode of feeding
- A short, strong, horny beak for pecking and picking up grains and insects.
- Strong, sharp claws on the toes for scratching the surface of the ground in search of food.
(b)(ii) Two adaptations for locomotion
- Fore-limbs modified into wings for flying, with a streamlined body that reduces air resistance.
- Strong, clawed hind limbs for walking, running and scratching, and tail feathers for steering and balancing.
(c)(i) Three observable inheritable characters
Colour of feathers, shape of comb and colour of the wattle. (Size of comb, shape of beak and body size are also acceptable.)
(c)(ii) Test cross to determine whether specimen C is homozygous or heterozygous dominant
White feather colour (W) is dominant over black (w). A white cock may be homozygous (WW) or heterozygous (Ww). To find out, carry out a test cross by mating it with a homozygous recessive black fowl (ww).
Case 1: if specimen C is WW
Parents: WW (white) \( \times \) ww (black)
Gametes: all W \( \times \) all w
Offspring: all Ww - every chick is white.
Case 2: if specimen C is Ww
Parents: Ww (white) \( \times \) ww (black)
Gametes: W and w \( \times \) all w
Offspring: Ww (white) and ww (black) in the ratio 1 white : 1 black.
Conclusion: If all the offspring are white, specimen C is homozygous dominant (WW). If about half of the offspring are black, specimen C is heterozygous dominant (Ww).
