BIOLOGY SS1 SECOND TERM LESSON NOTE
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BIOLOGY SS1 SECOND TERM LESSON NOTE
SECOND TERM E-LEARNING NOTE
SUBJECT: BIOLOGY CLASS: SS 1
SCHEME OF WORK
WEEK TOPIC
1. Reproduction (Meaning, Types and Form of Asexual Reproduction)
2. Sexual Reproduction (Conjugation, Meiosis) and Excretory Organelles in Living Cells
3. Reproduction in Unicellular Organisms and Invertebrates
4. Irritability and Movement
5. Nutrition in Animals (Food Substances and Digestive Enzymes)
6. Basic Ecological Concepts
7. Biomes
8. Population Studies
9. Functioning Ecosystem
10. Ecological Management
11. Revision and Examination
REFERENCES
· Modern Biology for Senior Secondary Schools by S.T. Ramlingam
· Essential Biology by M.C Michael
· New Biology by H. Stone and Cozen
· SSCE, past questions and answers
· New System Biology by Lam and Kwan
· College Biology by Idodo Umeh
· UTME, SSCE and CAMBRIDGE past questions and answers
· Biology practical text
WEEK ONE DATE ……………………
TOPIC: REPRODUCTION
CONTENT
- Meaning and Types of Reproduction
- Forms of Asexual Reproduction
- Sexual Reproduction (Conjugation and Fusion of Gametes)
- Meiosis and Importance of Meiosis
BIOLOGY SS1 SECOND TERM LESSON NOTE
MEANING AND TYPES OF REPRODUCTION
Reproduction is the ability of an organism to give rise to new individuals of the same species in order to ensure continuity of life.
There are two types of reproduction
a. asexual reproduction
b. sexual reproduction
a. Asexual Reproduction: is the process whereby an organism produces an offspring by itself. I.e. only one parent is presence. No gametes involved thus there is no fusion of nuclei, but the cells that give rise to the offspring usually divide by means of mitosis. Offspring produced are identical to the parent in all respect and are called clones
b. Sexual Reproduction: is a type of reproduction that involves two parents and the fusion of the male and the female gamete to form a zygote. Offspring produced show new variation. The sex cells (gametes) are produced by meiotic cell division and after fertilization the new individual continue to grow and produce new cells by mitosis.
EVALUATION
1. What is reproduction?
2. Why is reproduction necessary?
3. Differentiate between the two types of reproduction.
FORMS OF ASEXUAL REPRODUCTION
a. Binary Fission: Fission is the simplest form and involves the division of a single organism into two complete organisms, each identical to the other and to the parent. Fission is common among unicellular organisms such as bacteria, many protists and some algae.
b. Budding: The parent organism develops an outgrowth which subsequently forms the new individual organism. These buds break off from the parent without causing any injury and live an independent life. Budding is common in yeast and hydra
c. Spore Formation: Spores are DNA-containing capsules capable of sprouting into new organisms; unlike most seeds, spores are produced without sexual union of gametes, when dispersed, each spore is capable of developing into a new organism. Spores are common in lower organisms especially fungi such as rhizopus and penicillum.
d. Fragmentation: A part of the parent organism breaks up and develops into a new independent organism. This type of reproduction is also called regeneration. Fragmentation is common in spirogyra and coelenterates.
e. Vegetative Propagation: It occurs in higher plants. In this process, a new plant grows from any portion of an old one other than the seeds. There are two methods of vegetative propagation, this include natural and artificial vegetative propagations.
Natural vegetative propagation involves the use of vegetative parts such as stems, leaves, roots or buds. The part involved must have a store of food and sometimes able to act as a perennating organ i. e. enable the plant to survive from one growing season to the next. Organs of vegetative propagation include;
- Bulbil: Axillary buds growing from the veins of leaves e. g. Bryophyllum and Begonia.
- Runners or stolons: Stems that creep horizontally on soil surface. Buds and adventitious roots develop from the nodes of the parent plants e. g. sweet potato, grass.
- Rhizomes: Underground horizontal stem. It has scaly leaves which cover lateral buds at the nodes. Lateral buds grow into new aerial shoots e. g. ginger, canna lily.
- Corms: Underground stems which grow vertically in the soil. Buds develop from the axils of scale leaves, grow upward and form leaves and flowers e. g. cocoyam.
- Stem tubers: Underground stems which have swollen tips. Axillary buds on tubers give rise to new aerial shoots e. g. yam, sweet potato
- Suckers: Short underground horizontal branches e. g. banana, pineapple
- Bulb: Underground condensed shoots with compressed stems and scaly leaves e. g. onion, garlic.
Artificial propagation is the use of parts of the parent plant to multiply the plants. Budding, grafting, layering, cutting and marcotting are types of artificial propagation.
EVALUATION
1. List four types of asexual reproduction with examples.
2. Discuss spore formation in a named fungus.
BIOLOGY SS1 SECOND TERM LESSON NOTE
GENERAL EVALUATION/REVISIONAL QUESTIONS
1. List four forms of asexual reproduction giving one example of organism that exhibit each.
2. List four common natural vegetative parts in plant giving one example of plant in each case.
3. Describe five types of artificial vegetative propagation.
4. Briefly describe fragmentation in spirogyra.
5. Describe sporulation in amoeba.
READING ASSIGNMENT
College Biology, chapter 16, page 292 – 301
WEEKEND ASSIGNMENT
1. Bacteria multiply rapidly by A. fragmentation B. binary fission C. spore formation D. budding
2. The type of reproduction that is common to both Hydra and Yeast is A. conjugation
B. binary fission C. grafting D. budding
3. During asexual reproduction in paramecium, how many times does the zygote divide to produce eight nuclei A. 1 B. 2 C. 3 D. 4
4. Vegetative propagation is described asexual reproduction because A. reproductive organs are not involved B. many new plants are produced C. there is no exchange of genetic materials D. new individuals are not formed
5. Which of these organs of vegetative propagation is not a perennating organ? A. Rhizome B. Sucker C. Bulbil D. Bulb
THEORY
1. Describe two types of artificial propagation.
2. State three advantages and two disadvantages of asexual reproduction.
WEEK TWO DATE ……………………………
TOPIC: SEXUAL REPRODUCTION
CONTENT
· Sexual Reproduction
· Conjugation
· Fusion of Gametes
· Meiosis
· Excretion
SEXUAL REPRODUCTION
There are two types of sexual reproduction, this include conjugation and fusion of gametes.
a. Conjugation: the simplest form of sexual reproduction, as contrasted with asexual reproduction. This is observed in some unicellular organisms e. g. paramecium, fungi e. g. rhizopus, algae e. g. spirogyra. Two similar organisms (conjugants) join together and exchange genetic material contained in their nuclei. After the exchange, the organisms separate. The zygote or zygosphere form is capable of developing into a new organism.
b. Fusion of Gametes: This occurs in higher organisms where gametes (male and female sex cells) are produced in special structures by a process known as gametogenesis which involves meiotic cell divisions. Fertilization, the process in which haploid male and female sex cells fuse together to producing a single diploid cell (zygote) that develops into an adult organism occurs after gamatogenesis.
BIOLOGY SS1 SECOND TERM LESSON NOTE
EVALUATION
1. Describe conjugation in spirogyra.
2. Define spermatogenesis and oogenesis.
MEIOSIS
Meiosis is the reduction method of division that leads to the formation of four daughter cells that are haploids. Meiosis differs from mitosis, in that it involves two consecutive cell divisions instead of one and the genetic material contained in chromosomes is not copied during the second meiotic division. Whereas mitosis produces identical daughter cells, meiosis randomly mixes the chromosomes, resulting in unique combinations of chromosomes in each daughter cell. Meiosis ensures the chromosome number of an individual remains the same from generation to generation.
Meiosis consists of two successive divisions:
First Meiotic Division
a. Interphase: resting phase, chromosomes are not seen.
b. Prophase I: At early prophase, chromosomes contract and become clearly visible. At middle prophase, homologous chromosomes come together and spindle is formed. At late prophase crossing over takes place between homologous chromosomes at a place called chiasma.
c. Metaphase: Nuclear membrane disappears, the bivalent chromosomes assemble at the equator and are attached to the spindle by their centromere.
d. Anaphase: Bivalent chromosomes separate completely and move to the opposite pole of the cell.
e. Telophase: bivalent chromosomes arrived at the pole, nuclear membrane are formed around the chromosomes at the two poles, two daughter cells result with half the number of chromosomes in the parent cell.
Second Meiotic Division
It consists of four stages similar to mitosis, no resting stage and no replication of chromosomes. At the end, four daughter cells are formed.
Importance of Meiosis
Meiosis aids the formation of
a. Spermatozoa.
b. Ova or egg cells.
c. Pollen grains in flowering plants.
d. Ovules in flowering plants.
EVALUATION
1. What is crossing over?
2. Outline four life processes involving meiosis.
GENERAL EVALUATION/REVISIONAL QUESTIONS
1. Describe conjugation in Mucor.
2. Mention two structures each where meiosis takes place in plants and animals.
3. Describe sexual reproduction in hydra.
4. What is meiosis?
5. Outline four importance of meiosis to life.
6. List five excretory products in living organisms.
READING ASSIGNMENT
College Biology, chapter 16, page 301 - 305
WEEKEND ASSIGNMENT
1. The process which ensures that the chromosome number for each species of organism remain constant from generation to generation is called A. fission B. meiosis C. mitosis D. oogenesis
2. The cell organelle, from which spindle fibres originate during cell division in animal cells is known A. centrosome B. chromosome C. lysosome D. ribosome
3. In animals meiosis comes A. after fertilization B. after every mitotic division C. before fertilization D. before every meiotic division
4. One of the ways in which body cells differ from gamete cells is in A. Type of centromeres they contain B. Number of chromosome pairs they contain C. Type of chromatids they contain D. Number of chromosomes they contain.
5. Which of these excretory structures is not found in amphibians? A. Gills B. Lungs C. Skin D. Flame cell
BIOLOGY SS1 SECOND TERM LESSON NOTE
THEORY
1. In a tabular form, state five differences between
a. Mitosis and meiosis.
b. Sexual and asexual reproduction.
2. Explain the phases of meiosis.
WEEK THREE DATE ……………………
TOPIC: REPRODUCTION IN UNICELLULAR ORGANISMS AND INVERTEBRATES
CONTENT
· Reproduction in Amoeba(Binary and Multiple Fission)
· Reproduction in Paramecium(Sexual and Asexual)
· Reproduction in Spirogyra
· Reproduction in Earthworm
· Reproduction in Cockroach
· Reproduction in Housefly
· Reproduction in Snail
REPRODUCTION IN AMOEBA
Amoeba reproduces asexually by binary fission and multiple fission (sporulation) during adverse condition.
In binary fission when an amoeba reaches full size, it stops moving and divides into two equal parts starting from the nucleus. This is followed by the division of the cytoplasm, after which two daughter amoebae are formed.
In multiple fission amoeba becomes rounded and secretes around itself a cyst. Inside the cyst, the nucleus divides several times. When conditions becomes favourable, the cyst burst; each nucleus surrounded by a part of the cytoplasm of the parent. In this way, very small amoebae are formed.
BIOLOGY SS1 SECOND TERM LESSON NOTE
REPRODUCTION IN PARAMECIUM
Paramecium reproduces asexually by binary fission and sexually by conjugation.
Binary fission occurs under favourable conditions, the micronucleus divides into two equal halves by mitosis and each moves to the opposite side of the cell, the meganucleus elongates and the cytoplasm constricts after which two young paramecia are produced.
Sexual reproduction is by conjugation of two individuals of different lines of descent. Stages in conjugation include
1. Two matured paramecium come together and get fused by their oral grooves.
2. The micronucleus divides twice by meiosis and four nuclei are formed in each conjugant
3. The smaller micronuclei are exchanged between the two conjugants
4. The migatory micronucleus fuses with the stationary micronucleus in each conjugant to form a zygote
5. The zygote in each conjugant divides thrice to form eight nuclei
6. The ex-conjugant with four meganuclei and four micronuclei divide to form four paramecia each having a meganucleus and a micronucleus.
Conjugation in paramecium
EVALUATION
1. Describe binary fission in amoeba.
2. Describe sexual reproduction in paramecium.
REPRODUCTION IN SPIROGYRA
Spirogyra reproduces asexually by fragmentation and sexually by conjugation.
In fragmentation, when a filament reaches a certain length, parts of it break away and grow into new filaments
In conjugation
1. The cells of two filaments come to lie side by side and a conjugation tube is formed between them.
2. the cells in one filament act as the male gamete while the other act as the female
3. The male gamete passes through the conjugation tube to meet the female gamete and fuses to form a zygote.
4. The zygote secretes a resistant wall around itself and form a zygospore.
5. After a period of rest and favourable condition, the outer coats burst and a young filament grows out.
Earthworms are hermaphrodites i. e. each has both male and female sex organs and therefore produces both male and female gametes.reproduction is by sexual means.
Process of Copulation
Two worms to be engaged in copulation come to lie close together with their ventral surfaces touching. Copulation takes place at night outside the burrows. The reproductive organs of earthworms are anteriorly located. The worms lie in such position that the segments 9-15 of one worm are opposite the clitellum (segments 32-37) of the other and are held firmly by chaetae during copulation.
After copulation, the two worm separate. After few days eggs are laid and fertilized in a cocoon secreted by the clitellum. The development of the embryo takes place inside the cocoon and one worm hatches from a batch of eggs in one cocoon.
EVALUATION
1. Describe conjugation in a named alga.
2. What is hermaphroditism?
3. Describe the process of copulation in earthworm.
REPRODUCTION IN COCKROACH
Sexual reproduction takes place in cockroaches and fertilization is internal. Male and female cockroaches mates and the male introduces sperm into the genital opening of the female. The sperms are then stored in the sperm pouch until the eggs are released from the two ovaries. As the eggs are released, they are fertilized by the stored sperm. Fertilized eggs are laid (about 10–16 eggs) in a horny egg case (ootheca) which the female carries in her abdominal pouch for some time and later deposit it in a safe dark place. After 30 – 100 days, the eggs hatch into nymphs which are wingless, small and whitish in colour.
The nymphs feed, grow, and become brown, moult about 13 times to become adults.
In the process of moulting, the wings first appear as wing pad and later develop into full grown wings. Cockroaches require 11 – 20 months to develop from eggs to imagos. Metamorphosis is incomplete.
REPRODUCTION IN HOUSEFLY
Adult male and female mates and within two to three days fertilized eggs are laid. The laying of eggs takes place in the day light. Housefly undergoes complete metamorphosis.
2 – 7 batches of eggs (100 – 150 eggs in a batch) are laid by the female housefly in a moist dirty environment. The eggs hatch into white larvae in about 8 – 24 hours.
The larva called maggot has a segmented body. The head bears a pair of hook for tearing food and drawing the larva along. On the ventral surface of the segmented body lie spiny pads for movement. It has two pairs of spiracles for breathing. The larva moults several times and lasts for about 5 – 14 days after which it moves to a dry place to begin the pupal stage.
The maggot shortens; its skin becomes hard and brown forming the pupal case (puparium). It does not feed or move. Internal re-organisation takes place at this stage. In about 3 – 10 days, the young adult hatches out of the puparium.
The adult housefly called imago emerges from the puparium using a sac-like organ (ptilinum) to break it open. It moves to the surface of the dirt and flies away when the wings are dry.
BIOLOGY SS1 SECOND TERM LESSON NOTE
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