Science F3 Chapter4 Reproduction

7/31/2019 Science F3 Chapter4 Reproduction

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Chapter 4

Reproduction


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Sexual & Asexual Reproduction

Reproduction : production of a new

generation of individuals (offsprings) from

pre-existing ones (parents)

Importance : ensure continuity

Two types :

1. Asexual

2. Sexual


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Sexual & Asexual Reproduction (contd)

Asexual

Formed from one parent

Genetically identical to each other and to the

parent

Five major types:

1. Binary fission

2. Budding3. Spore formation

4. Vegetative reproduction

5. Rejuvenation


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Binary fission

Unicellular organisms divides into two parts

Example : amoeba, paramecium

Budding

Parents produces an outgrowth of bud, detached to become new individual

Examples : yeast, Hydra

Spore formation

Seen in bacteria, fungi

Formed in spore-bearing structure - sporangium

Each spore become new individual

Rejuvenation

Replacement of parts that are lost due to injury

Results to two or more individual

Vegetative reproduction

Part of a plant detached and grows into new plants

examples of parts : roots, stem, leaf, bud


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Sexual & Asexual Reproduction (contd)

Sexual

By fusion of specialised sex cells (gametes)

Male gamete (sperm) fuses with female

gamete (ovum/egg) during fertilisation

form zygote

2 types of fertilisation

Internal fertilisation External fertilisation


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Sexual & Asexual Reproduction

Similarities

Involves the production of a new generation ofindividuals of the same species

Asexual Differences Sexual

One Number of parents

involved

Two

No Gametes involved Two; male and female

Identical with parents Genetic make-up ofoffspring

Different, show geneticvariation

Large amount of offspring Offspring Fewer offspring

Rapid Speed of reproduction Less rapid


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THE MALE & FEMALEREPRODUCTIVE SYSTEM


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Male Reproductive System


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Male Reproductive System (contd)

Organ Function

Testis Produce sperms

Scrotum

Holds the testes outside the body

Protects the testes

PenisPlaces sperms in the vagina during sexual

intercourse

Urethra Carries sperm and urine out of the body

Sperm ducts Carry sperms from the testes to the urethra

Seminal vesicleProduces fluid that provides nutrients to the

sperms

Prostate glandProvide fluid which neutralises the acidity of urine

and female vagina


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Female Reproductive System


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Female Reproductive System (contd)

Organ Function

Ovary Produce ovum (eggs) and female hormones

Uterus (or womb) Place where the embryo develop

Fallopian tubeCarries ovum from the ovary to the uterus

Fertilisations happens here

VaginaPlace where sperm are deposited

Birth canal

CervixSecrets mucus which enhances sperm movement to

the uterus


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Male & Female Gametes

Male gametes

Sperm

Consists of a head, a

middle piece and a long

tail

Role : swim towards the

female gamete (ovum)


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Male & Female Gametes (contd)

Female gametes

Ovum

Larger than sperm

Spherical shaped

Only one ovum is

produced every menstrual

cycle


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Male & Female Gametes (contd)

Aspect Male gameteFemale

gameteNotes

Size Very small Larger

Size of ovum = 0.1 mm

Size of sperm = 0.0025 mm (at

the widest region of the head)

Number Large numbers Very few

A healthy male produce about

300 millions sperm per day

Only an ovum is produced every

menstrual cycle

Mobility Motile Non-motile

Whip-like movement of the tail

propels the sperm towards the

ovum


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Changes in the male and female during

puberty

Male Female

Moustache and beard Produce ovum

Release semen

Show interest in females

Produce semen &

Enlargement of breasts and buttocks

Larger bones and muscles

Begins to menstruate

Pubic and armpit hair

Show interest in males

Accumulation of fats under the skin

Voice become hoarse


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The Menstrual Cycle

Menstrual cycle

Repeated cycle of event

Occur every 28 days from puberty (when ovum

production begins) to menopause (when ovum

production stops)

Discharge of dead ovum, blood and uterus wall


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The Menstrual Cycle

Personal hygiene during menstruation

Wear a clean sanitary pad

Change the sanitary pad frequently

Bathe as usual to maintain body cleanliness

Wrap used sanitary with a paper or plastics


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FERTILISATION AND PREGNANCY


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Fertilisation and Pregnancy

Fertilisation sperms meet ovum in the

fallopian tube

Will form zygote, the move through the Fallopian

tube


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Upon reach the uterus, it will become embryo

Implantation the embryo sticking to the

uterus wall


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Placenta place where exchange of

substances occur Umbilical cord connects embryo to the

placenta


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At placenta

Food and oxygen move from mother to the

baby

Waste products like carbon dioxide and urea is

eliminated


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Science F3 Chapter4 Reproduction

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