Unit 4 Cells, Human Reproduction and Heredity
(Extension parts are highlighted in blue italics.)
Students should learn Students should be able to Suggested learning and teaching activities
4.1 Cells - the basic units of living things
Basic structure of a cell Recognise cells as the basic unit of living things
Distinguish between plant cells and animal cells
Use a microscope to examine prepared slides of plant and animal tissues
Identify the basic structures of cells, including cell wall (in plant cells), cell membrane, cytoplasm, nucleus, vacuole, chloroplasts (in plant cells)
State the functions of the basic structures of cells
Examine photomicrographs or prepared slides of various types of plant and animal cells
Prepare slides of plant and animal tissues (e.g. onion and ox eye cells), examine these slides under a microscope and draw diagrams of the observed cells
DNA as the genetic materials and the book of life
Recognise that the chromosomes found in the nucleus of each cell contain the genetic materials, DNA
State that there are 46 chromosomes in a human body cell
Recognise that human male and female cells have different sex chromosomes
State that DNA encodes the instructions that determine our different traits
View animation of the structural relationship between chromosomes and DNA found in the nucleus
Examine photomicrographs of the set of chromosomes found in a male and a female human cell
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Cells can divide, grow and differentiate Recognise that cells can divide, grow and differentiate into different types of cells
View animations or video clips about cell division
Level of organisation of living things State that the level of organisation in most living things is cells, tissues, organs and systems
Recognise that organs in different systems are specialised for carrying out different functions in living things
Examine a human torso to identify the organs in different systems
Observe pig’s liver and lungs for the various kind of tissues in different organs
Observe the different organs (e.g. flowers, leaves, stems and roots) of a potted plant
4.2 Human reproduction
Reproduction State that reproduction is an essential life process to ensure the continuity of humans
Sexual maturity and secondary sexual characteristics
Recognise the signs of maturation of the reproductive system during puberty
Describe the secondary sexual characteristics appear during puberty
Watch video clips about puberty
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Students should learn Students should be able to Suggested learning and teaching activities
Reproductive systems
Identify the different structures of the male and female reproductive systems and recognise the functions of these structures
Examine a human torso to identify the different structures of human male and female reproductive systems
Sex cells: sperm and ovum Identify sperms and ova as the male and female sex cells respectively
State that a sperm and an ovum each carry one set of chromosomes
(23 chromosomes) in humans
Examine prepared slides of sperms and ova
Examine photomicrographs of the set of chromosomes found in human sex cells
Fertilisation and implantation Recognise that fertilisation occurs when a sperm fuses with an ovum
State that the zygote formed from fertilisation carries two sets of chromosomes (46 chromosomes)
State that development of the embryo begins from the implantation in the uterus
Recognise the development of the embryo inside the mother’s body and the birth of a baby
Watch a video clip on the development of embryo from the fertilisation of sperm and ovum
Watch a video clip on foetal development and the birth giving process
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Students should learn Students should be able to Suggested learning and teaching activities
Pregnancy and parenting State the signs and the length of pregnancy
Be aware that parenting is essential for the growth of infants
Search information on some health advices during pregnancy (e.g. no smoking)
Search information on the length of pregnancy and the needs of parenting in other mammals
Family planning and birth control Be aware of the need of family planning
Understand that prevention of the fusion of ovum and sperm is one of the basic principles of birth control
Recognise the various methods of birth control
Recognise that some birth control methods can help prevent the transmission of sexually transmitted diseases
Watch video clips on various methods of birth control
4.3 Heredity and variation
Heredity State that heredity is the passing of traits from one generation to the next as a result of the transmission of genetic information
Construct a “genetic traits tree” to analyse the passing of a trait in a family
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Students should learn Students should be able to Suggested learning and teaching activities
Variation Recognise that variations are determined by heredity and the environment
Give examples of continuous variation and discontinuous variation in humans
Construct and interpret bar charts and histograms showing the distribution of variations in a group
Search information on some continuous and discontinuous variations in humans
Conduct a survey about a discontinuous variation in the class and present the data in a table and in a bar chart
Conduct a survey about a continuous variation in the class and present the data in a table and in a histogram
Identical and non-identical twins Distinguish between the occurrence of identical and non-identical twins
Recognise that variations between identical twins are due to differences in their experiences and the environment
View animations about the formation of identical twins and non-identical twins
Discuss about the factors affecting the differences between a pair of identical twins
DNA and heredity State that there are only four different kinds of bases, A, T, C and G on the DNA
State that the double helix structure of DNA is based on the base pairing of A with T and C with G
Recognise that the instructions encoded in DNA depend on the sequence of bases on the DNA
Construct an origami model of DNA, or a candy DNA model to demonstrate the double helix structure as well as the base pairing
Design a coding system for the 26
alphabets using DNA bases and write the message in a string of DNA bases to a friend for decoding