THEME : INVESTIGATING THE CELLS AS A BASIC UNIT OF LIVING THING

LEARNING AREA : 4. CELL DIVISION.LEARNING OBJECTIVES : 4.2 : UNDERSTANDING MEIOSISLEARNING OUTCOMES :

1. State the necessity of trait inheritance in offspring for continuation of life.

2. State the necessity to maintain diploid chromosomal number from generation to generation.

3. State the necessity for production of haploid gametes in sexual reproduction.

4. State the significance of meiosis.5. Identify the type of cell that undergoes meiosis.6. Explain the process of meiosis.7. Arrange the various stages of meiosis in the correct

order.8. Compare and contrast meiosis and mitosis.

TASK :

1. State the necessity of trait inheritance in offspring for continuation of life.To ensure all individuals of the same species have the same chromosomal number. In order for the offspring to have the same chromosomal number as their parents, the cell must undergo meiosis.

2. State the necessity to maintain diploid chromosomal number from generation to generation.The number of chromosomes present in the nucleus of each cell is constant for the species concerned.

3. State the necessity for production of haploid gametes in sexual reproduction.Sexual reproduction involves the fusion of two haploid gametes during fertilization. This result in the formation of a diploid zygote.

4. State the significance of meiosis.

Meiosis ensure that the diploid number of chromosomes is maintained from one generation to the next.

5. Identify the type of cell that undergoes meiosis.

The type of cell that undergoes meiosis in human, animals & plants

Cell

Human/Animals Plants

♂ ♀ ♂ ♀

Sperm ovum pollen ovule

Organ testes ovaries anthers ovaries

6. Explain the process of meiosis.Meiosis is the process of nuclear division. It reduces the number of chromosomes in new cell to half the number of chromosome in the parent cell.

7. Arrange the various stages of meiosis in the correct order. Rearrange the stages of meiosis in the correct order.

Metaphase I Prophase ITelophase II Metaphase IProphase II Anaphase IAnaphase I Telophase I

Metaphase II Prophase IIProphase I Metaphase IITelophase I Anaphase IIAnaphase II Telophase II

8. Compare and contrast meiosis I and meiosis II.

COMPARE AND CONTRAST MEIOSIS I & MEIOSIS II

Four non- identical nucleus/cells are formed

Two non- identical nucleus/cells are formed

Two cytokinesis occurTelophase

Only one cytokinesis occur

Chromatids are separated at the centromere and moved to the opposite poles

Anaphase Chromosomes homologous are pulled away from one another and move to the opposite poles of the cell

I ndividual chromosome ( two chromatids ) lined up on the metaphase plate

MetaphaseTetrad are lined up on the metaphase plate

n chromosomes2n chromosomes

Chromosomes seen as two chromatid tied by centromere

End prophaseChromosomes seen as tetrad (4 chromatid) which are attach at chiasmata

No synapsisSynapsis between homologous chromosomes

No replication of chromosomesEarly Prophase

Replication of chromosomes

Meiosis I IPhaseMeiosis I

9. Compare and contrast meiosis and mitosis.

CELL DIVISION

Similarity

Mitosis meiosis

Division process

Differences

Occur

Necessity

Nucleus division

synapsis

Gamete cellSomatic cell

To produce gameteGrowth, to replace the dead cell

Two

occurNot occur

One

Crossing over

Numbers of daughter

Numbers of chromosomein the daughter cells

Genetic contains ofdaughter cells

Genetic variation

Occur at the end of prophase

Not occur

Four

Haploid (n)

Different

Has variation genetic

Two

Diploid (2n)

Same as parent cells

No variation genetic

10.Describe what will happen when the movement of chromosomes during mitosis and meiosis do not occur in and orderly manner.

11.Know and avoid things that maybe harmful.

Interruption in movement of chromosomes in mitosis and meiosis

Abnormal Zygote

Downs Syndrome

How to preventKnowledgeAvoiding

Can cause

example

Slanted eyes

Short stature

Mental retardation

characteristic

aboutfrom

by

Environments agent can disturb mitosis & meiosis process

Eating preserve food

Radiation exposure

radiation Carcinogenic chemical

by