Background Information

Species of organisms survive and still continue their existence through the process of reproductIon.Reproduction can be asexual or sexual

Sexual reproduction: Sexual reproduction involves two sex cells called gametes. Two critical events that take place in sexual reproduction are: Meiosis and Fertilization.

Meiosis is a cell division that gives rise to gamete (sexcell) which has a haploid number of chromosomes (n) while fertilization is the fusion of the nucleus of the male and female gametes to give rise to a zygote which has a diploid number of chromosomes (2n).

Sexual reproduction requires male and female gonads (which are gametes producing parts); energy and food for gamete production, development of new organism and reproductive behaviour that will enhance the presence of mature male/female gametes at the place of fertilization at the right time.

Advantages of Sexual Reproduction:

One main advantage or importance of sexual reproduction is the Genetic variation that results from it during meiosis and fertilization which gives rise to the following benefits:

1. Proper and better adaptation of species to the environment.
2. Ability to survive unfavorable environmental conditions which will promote life continuity.

Among all vertebrates; there are individual males and females of separate sexes. Mature gametes from each of the opposite sexes can only be brought together at the right time for fertilization to occur. This is achieved by mating or copulation among the opposite sexes.

Reproduction in Fishes and Amphibian

Fishes: Reproduction takes place in an aquatic environment, it is characterized by the following features and events:

• Lays numerous egg in most cases.
• External fertilization in most cases.
• Eggs hatch into larvae.
• Oviparity (laying of egg).
• No parental care.
• Wasteful Reproduction process.

Amphibians e.g Toads and frogs

• Reproduction takes place in an aquatic environment.
• Fertilization is external
• Oviparity
• Distasteful gelatinous layer protects the eggs from being eaten.
• Fertilized eggs hatch into larva
• There is complete metamorphosis
• Small portion of the larva develop into adults
• No parental care.
• Reproduction is wasteful.

Sexual Reproduction in birds

• Reproduction takes place in a terrestrial external environment.
• Fertilization is internal
• Oviparity
• They do incubate their laid eggs
• The eggs are hatched into young ones
• There is parental care and
• Reproduction process is not wasteful.

Sperm Production

Sperms are produced by the seminiferous tubules of the testis. These tubules are lined with layers of actively dividing cells. These cells migrate, enlarge and undergo meiosis to bring the process of sperm production with the formation of spermatids. These spermatids mature into non-motile spermatozoa, which are carried passively to the epididymis. They mature into motile sperms which eventually move to the sperm duct. This whole process takes about 72days to take place. The sperm at the sperm duct can remain active for three months.

Sperm production in male humans begins at puberty and continues till old age. Up to 300 million sperms can be produced in a day by the seminiferous tubules.

Ova maturation and the menstrual cycle

Females are born with ovaries which contain potential egg cells called primary oocytes. The production of mature ova is a cyclic process which involves certain events that take place in the ovary (ovarian cycle) and the uterus (uterine cycle).

The ovarian cycle:

Each oocytes is surround by a structure called follicle – an actively dividing granular cell. The oocytes receives nutrients from the follicle.

A mature follicle is called Graafian follicle. Follicle secrete ooestrogen hormone. The secretion of oestrogen increases with the maturity of the follicles. The follicles become filled with fluid and pushes the oocytes to one side as they mature. A mature follicle (graafian folloicle) contains a secondary oocytes. The follicle bulges on the surface of the ovary and finally splits the ovarian lining and releases the egg into the abdominal cavity. This is called ovulation and normally only one of the follicles becomes mature to produce one ovum (egg). The released egg has a protein coat called zona pellucidia and layer of granular cells surrounding it. The ovum eventually gets wafted into the oviduct.

Ovulation takes place about day 14 from the beginning of the cycle. The Graafian follicle developes into corpus Luteum after releasing the ovum. Corpus luteum secretes progesterone and little oestrogen hormones. It shrivels if fertilization and implantation does not occur while the unfertilized egg dies.

Uterine Cycle:

This aspect of menstrual cycle involves the tickening of the endometrium at the uterus and the increase in supply of blood to it in readiness for implantation of the zygote. If fertilization does not occur, the endometrium breaks down. Blood and some endometrium tissue then leave the body through the vagina opening. This is called menstruation. Both the uterine and ovarian part of the cycle make up the menstrual cycle. The process is controlled by ostrogen, projesterone, follicle stimulating hormone and luteiuzing hormone.

Flower Structure

There are four whorls that make up a flower. They are: The sepals (collectively called calyx). The petals (collectively called corolla), The stamens (collectively known as Androecium) and The carpel's (collectively called Gynoecium's).

Pollination in Plants

Pollination is the transfer of pollen grains from the anters to a receptive stigma of a a flower of the same plant species. Pollination is of two types (i) self pollination and (ii) Cross pollination

1. Self Pollination:

A type of pollination that takes place when mature pollen grains from the anter of a flower falls on the stigma of the same flower (for example wheat and pea) or another flower of the same plant (for example: maize).

It is favoured, enhanced or facilitated by:
1. Homogamy: (carpels and stamen in bisexual flowers maturing at the same time) example: Mirabilis.
2. Cleistogamy: Condition in which bisexual flowers refuse to open and in such closed condition the pollen grain, are discharged directly onto the receptive stigma. Example isLegumes such as groundnut.

2. Cross pollination :

A type of pollination in which mature pollen grains of a particular flower are transferred to the stigma of another flower in another plant of the same species or closely related Species. Cross pollination is favoured or facilitated by:

1. Unisexuality in flowers
2. Dichogamy: A condition of bisexual flowers of flowering plants having their stamens and carpel mature at different times.
3. Self – incompatibility: An inherited condition, in which bisexual flowers of the same stamens bear stamens and carpels which mature at the same time but which are incompatible to each other for sexual reproduction.

Pollinating Agents: This includes: Wind , Water, Insects and some other animals like birds, bats squirrels and snails. Wind and insects are the major pollinators.

Wind pollination: Flower that are pollinated by wind are called anemophilous flowers. They have the following characteristics:

• Small and not conspicuous, they are borne in large inflorescences.
• Flowers are unisexual with both male and female occurring in the same plant.
• Sepels and petals when present are pale or green coloured.
• No scent or nectar
• Simple flower structure.
• Mature stamens hang outside the flower while the anters are large and they produce large quantities of pollen grains.
• Also the stigmas hang outside the flower on long flexible styles this provide large surface area for trapping pollen grains.

Insect pollination: Insects pollinated flowers are called entomophilous flowers. They have the following characteristics:

• Usually large and couspicious flowers.
• Bisexual flowers
• Brightly coloured and large petals.
• Scented flowers which produce nectar
• There is an elaborate structural modification of the flower to suit its insect pollinator
• Also the stigmas lie within flowers

General questions

1. In sexual reproduction meiosis leads to the formation of while fertilization leads to formation of

2. Fertilization gives rise to an organism with number of chromosomes

3. During meiosis number of daughter cells are formed and each cell has a number of chromosomes.

4. An individual organism that produces both eggs and sperms is called a

5. Write two examples of the organism in question '4'

6. In sexual reproduction, oviparity is an act of _______ It can be found among _________ and _____________

7. In vertebrates external fertilization occurs among and

8. One essential environmental condition for external fertilization to take place among vertebrates is an environment.

9. Eggs that are layed by reptiles and birds after fertilization are called eggs.

Use the diagram below to answer question 10 – 15

Identify and label the parts, numbered 10 – 15 and state their functions as tabulated

16. In vertebrates, parental care for the young ones in reproduction is observed mostly among and

17. State two functions of male sex hormone (testoterone) in secondary sexual characteristics

18. Sperms are produced at the cells lining of the and stored at the

19. Write three functions of these accessory glands in the male reproductive organ: Seminal vesicles, prostrate glands and the cowper's gland

20. In male reproductive sytem, which structure connects the epididymis to the urethra?

21. The openning at the penis is called a urino genital opening because

22. State the hormone that directly causes ovulation

23. When does the ovum undergo its second meiotic division?

24. After releasing the ovum (egg cell), the Graafian follicle develops into
A yellow solid that secretes

25. When is a female mammal said to be on heat.

26. What happens to the endometrial tissue in the uterus if implantation does not occur

27. Where in the female repoductive system does ovulation take place?

28. The main reproductive parts among the four whorls of a flower are _______ and _________

Label the diagram numbered 29,30,31 and 32

33. State the names of each ovary in relation to its position to the receptacle in the diagram in fig 4.95

34. Identify and label the ovary, style and stigma in each diagram(see fig 5.7e, f,g)

35. What is an Anemophilous flower?

36. What is a complete or perfect flower?

37. When male and female flowers are found on the same plant, it is said to be while different plants having male and female flowers are said to be

38. A is an example of an animal that displays courtship behaviour by auditory signals.

39. Cleistogamy is a characteristic in flowers that encourages pollination.

40. The two main pollination agents are and

Expression Exercises

1a. Write two advantages of sexual reproduction over Asexual reproduction.

1b. State two reasons why sexual reproduction in fishes and amphibians is wasteful

2b. Below is a diagram of developing young inside the uterus of a female mammal. Use it to answer question 2b.

Identify the following parts in the table with a leading line on the diagram and label accurately also write their function in the table.

3a. How is circulating system of the embryo separated from the mother?

b. What is menstrual cycle?

c. Once fertilization takes place, What prevents other sperms from entering an egg.

4. Write three features that favour cross-pollination

b. Write four characteristics of an entomophilous flower and three characteristics of anemophilous flower

1. Observing the reproductive organ of a freshly dissected male rat.
Your teacher will dissect a male rat with its reproductive organ exposed.

Materials required:
1. Freshly dissected male rat with exposed reproductive organs
2. Identify the following parts in the dissected specimen
   1. The testis
   2. The vas deferens.
   3. The seminal vesicle
   4. The penis and
   5. epididymis.
3. Make up to 10cm diagram of what you observed ( the dissected rat reproductive part) and label the major parts.

(i) Where are the male gametes produced from your specimen observation

(ii) Do rats breed through out the year?

(iii) How does breeding among rats differ from that of frogs?

2. Observing the reproductive organs of a freshly dissected female rat.

1. Repeat the procedure in 1 above using a freshly dissected female rat.
2. Also idenify the following: Ovary, Oviduct, and Uterus.
3. Draw 10cm size of what you have observed, labelling the part that where identified in (ii).

(i) From your observed specimen, where are the female gametes produced?

(ii) Where does the fertilization of those gametes occur

(iii) How long does gestation period last in the mammal under investigation

3. Examining the eggs of vertebrates
Collect the eggs of bird and lizard

1. Examine their external structural differences and appearances
2. Draw the internal structure of any of the two eggs, identify and label the important structures.
3. Which of the eggs receives much parental care

4. Examinning the parts of a flower
Materials/Apparatus: Pride of Barbados or hibiscus flower, hand lens,

1. Hold the flower by its green stalk i.e. the pedicel and examine its general external features.
2. Identify and observe the sepals and remove and count them. Then record the number.
3. Identify and carefully observe the petals, remove them and count how many they are.
4. Using the hand lens, carefully observe the stamens. Remove the stamens and locate the anthers.
5. Use the hand lens to view the internal central structure which is the pistil. Identify the stigma, style and ovary. Particularly note the arrangement there.

From your observations in the experiment supply the information at the vacant spaces in the table below concerning the flower you have studied.

(b) Suggest the function of the corolla (the petals) in the flower

Observing a half section of a flower.
Material required:

Flower of pride of Barbados or hibiscus; scalpel or razor blade, hand lens.
First study the diagram below which will guide you in your investigation and observation.

(i) Take a flower; starting from the pedicel, cut it into two halves longitudinally using the scalpel or razor blade

(ii) Use a hand lens to examine the section of the half flower while the flower is placed on the bench.

(iii) Make a well Labeled diagram of the structure in your biology practical notebook.

Questions:

(i) Write down one content of the ovary of the flower

(ii) What is the name given to the arrangement of the ovules in the ovary

(iii) What type of such arrangement is present here?

Examine the diagram in fig 4.8 carefully. Use it to answer the questions that follow.

(i) Identify the diagram without reasons

(ii) Where is it produced in humans

(iii) What hormone stimulates the production of the specimen diagram

(iv) Label the parts of the diagram labeled A B C

(vi) What is the purpose of the part labeled A in the function of the diagram specimen during sexual reproduction

(a) Which of the flowers in the diagrams above is male and which one is female

(b) Does the flower favour insect pollination or wind pollination? Gave reason for your answer

(c) Write two exmples of:

(i) a dioecious plant and two examples of a (ii) Monoecious plant.

(ii) Monoecious plant.

Nov 1990 1a and b
1.a List three features which are essential for cross pollination to take place.

b. State three characteristics of wind-pollinated flowers

3.
Specimen E-Pride of Barbados
Specimen F- Maize plant flower

(a) Identify specimen E and F

(b) Suggest the agent of pollination of Specimen E

(c) Give three reasons for your suggestion in (B)

(d) In a tabular form, state three difference between specimen E and F

(c) With a sharp blade or scalpel, cut a longitudinal section of specimen E, to produce two equal parts of specimen E. Make a labelled drawing 10cm to 12cm long, of one half of specimen E.

May/June 2001 Q2

Specimen C, a pride of Barbados flower is provided.

4. (a)i. Identify specimen C

(ii). What is the symmmetry of specimen C?

(iii). Using the scapel/knife or razor blade provided, cut through specimen C longitudinally, diving it into two equal halves. Make a labelled drawing of 8cm to 10cm long of one half.

(iv). What is the common name given to specimen C? Name its placentation.3

(v). Mention two elements contained in the class of food produced by specimen C

June 1999 Q3
Specimen K: A hibsicus flower or pride of the barbados

(b) Cut Specimen K longitudinally into halves. Observe the halved specimen K and use it to answer Questions (b) (i) – (v)

(i) What is the symmetry of specimen K

(ii) Classify specimen K in relation to its reproductive structures

(iii) Name the type of placentation of specimen K

(c) Detach the sepals and petals of the longitudinal section of K and make a labelled drawing of 10cm to 12cm long to illustrate the features of the remaining parts of specimen K

(d)

1. Name the agent of pollination of K
2. Give one example of the agent of pollination of specimen K
3. State four adaptive features of specimen K that attracts the agent you have mentioned

June 2005 WASSCE BIOLOGY 1 PRATICAL-QUESTION (Part 111)

4(d)(i) Carefully detach two petals from specimen I making sure that the special petal is left intact, make a labeled drawing 10 -12cm long of the remaining portion of specimen I.

(ii) what is the function of the special petal?

(iii) Classify specimen I into its phylum and class.

(iv) State three pollinating agents of specimen I.

(e) State two observable adaptations for survival in specimen J.

June 2008 WASSCE BIOLOGY 1 PRATICAL-QUESTION

You are provided with pride of Barbados flower as specimen A, a legum/pod (beans)

1. (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. (11marks)

(ii) What type of ovary is present in specimen A?(1marks)

(iii) Give one reason for your answer in 1(a) (ii) above. (1mark)

(iv) Describe the petals and sepals of specimen A. (2marks) (v) What is the function of the special petal?(1mark)

(vi) State three features of specimen A which have led to the success of flowering plants. (3marks)

(b)(i) What type of fruit is specimen B? (1mark)

(ii) Give two other examples of the fruit type. (2marks)

(iii) State the mode of dispersal of specimen B.(1marks)

(iv) State two biological importance of the class of fruit to which specimen B belongs. (2marks)