Year 7B Reproduction

© Tony P. Thould

September 2000

REPRODUCTON

In order for a plant or animal species to survive they must reproduce.

Most plants and animals reproduce by sexual reproduction which involves a male sex cell joining with a female sex cell. This is called fertilisation.

1. Why do some animals/ plants produce only a few young whilst others produce hundreds or thousands?

2. What is an endangered species?

3. What is the difference between Internal and External Fertilisation?

4. In what ways can Man help Plants / Animals to survive?

Minimum you must answer is Questions 1,2 and 3.

AN OVUM CELL

Contains the female set of chromosomes.

Allows only one sperm inside before blocking any other

ones from getting in

Nucleus

Cell Membrane

A SPERM CELL

Tail for swimming

Nucleus with male

chromosomes

Acrosome to make a hole in the ovum wall for the sperm to get into the ovum

Mitochondrion to make energy to move the tail

Its job is to fertilize the ovum ( egg ) cell Test

Fertilisation

The Sperm cell uses its tail to swim

to the Ovum

The Acrosome dissolves a hole in the Ovum wall and one Sperm enters

FERTILIZATION

Pollen + Ovule = Seed

Carries the Male

Chromosomes in its Nucleus

Contains the Female Chromosomes in its Nucleus

These are each a HALF SET of Chromosomes so that when they

join together they form a WHOLE SET in the seed.

A Fully Fertilized

Ovule

FERTILIZATION

Sperm + Ovum = Foetus

Carries the Male

Chromosomes in its Nucleus

Contains the Female Chromosomes in its Nucleus

These are each a HALF SET of Chromosomes so that when they

join together they form a WHOLE SET in the seed.

A baby with a full set of

Chromosomes

FERTILIZATION

There are two types of fertilisation :-

EXTERNAL

This takes place outside the female body e.g. Frogs,

where the female lays her eggs in water and

the male sheds his sperm over them

INTERNAL

This takes place inside the female

body e.g. Man, where the sperm are placed

inside the females body and they swim

to the Ovum.

The female lays her eggs in a shallow hollow in the

sea bed

Male releases his sperm into the water nearby

EXTERNAL FERTILISATION

Fertilisation takes place outside the females body

GERMINATION

Once the seeds have been dispersed they need the right conditions to start growing into a new plant - Germination.

These conditions are:-

•Warmth

•Moist

•Air

•Light/Dark

THESE ORGANS HELP WITH REPRODUCTION

The male sex organs are made up from the Penis, Testes and Scrotum. The Testes make Sperm which contain the male genes. The Penis places the sperm as near as it can to the female’s egg ( Ovum )

The female sex organs are made up from the Ovaries, Vagina, Uterus and Oviduct. The ovaries make the Ovum which contains the female genes. The Uterus ( womb ) holds the developing baby.

THE MALE SEX ORGANS

Bladder

Seminal Glands

Sperm Duct

Testicle

Penis

Erectile Tissue

Pubic Bone

THE FEMALE SEX ORGANS

Ovary

Uterus or Womb

Cervix

Vagina

Ovum released from the ovary into the Oviduct

Oviduct

In a flowchart draw and label the path taken by a Sperm Cell from leaving the Testicle to fertilising

the Ovum Cell

THE MAIN PARTS OF A FLOWER

Sepal

Stamen

Petal

CarpelFilament

Anther

Stigma

Style

Ovary

TestOvule

THE FUNCTIONS OF THE MALE PARTS

Stamen

Anther

Filament

Makes pollen which has the male genes in it

Holds the Anther up in the air so that visiting insects brush against it

Different plants have different numbers, shape and sizes of Stamens

Test

THE FUNCTIONS OF THE FEMALE PARTS

Stigma

Style

Ovary

Carpel

A sticky surface where pollen stays

when visiting insects brush against it.

Guides the pollen tube down to the

Ovary.

Makes the Ovules which contain the

female genes. Forms the fruit.OvuleTest

THE FUNCTIONS OF THE MALE PARTS

Stamen

Different plants have different numbers, shape and sizes of Stamens

THE MENSTRUAL CYCLE

Every month once puberty has been reached, an egg or Ovum is released from one of the ovaries in the female. This is called Ovulation.

If the Ovum is not fertilised then it leaves the body through the Vagina along with the lining of the Uterus which had become thicker and richly supplied with blood.

This happens every month and is known as a Period or Menstrual Cycle.

Day 7

Day 14Day 21

Day 28

THE MENSTRUAL

CYCLE

THE MENSTRUAL CYCLE

Week One

An Ovum is made in the Ovary ready to be released into the funnel of the

Oviduct.

Oviduct

Ovary

Uterus

Vagina

THE MENSTRUAL CYCLE

Week Two

The Ovary releases the Ovum into the

funnel of the Oviduct. This is

Ovulation.

The Uterus wall thickens ready for the fertilised Ovum

Week Three

The Ovary travels down the Oviduct

towards the Uterus.

THE MENSTRUAL CYCLE

The wall of the Uterus is well supplied with blood.

THE MENSTRUAL CYCLE

Week Four

As the Ovum was not fertilised, the

Uterus wall is shed with the Ovum -

the Period.

THE MENSTUAL CYCLE

Once the period has finished the whole cycle begins again and continues each month as long as the Ovum is not fertilised.

To prevent the fertilisation of the Ovum many couples take precautions which stops the Sperm reaching the Ovum -

Contraception

EARLY PREGNANCY

The Embryo ( baby ) is held in the wall of the Uterus and is joined to the Placenta by the Umbilical Cord.

The baby gets food and oxygen from the mothers blood through the Placenta. It also gets rid of waste into the mothers blood through the Placenta

THE PLACENTA

Placenta

The Placenta forms a barrier between the blood of the mother and the baby but allows substances to pass between them.

THE PLACENTA

Placenta

Oxygen, sugar, protein, vitamins, minerals, water, antibodies all pass from the mothers’ blood, along the Umbilical Vein in the umbilical cord to the baby.

THE PLACENTA

Placenta

Waste products such as Carbon Dioxide, Urea and excess salts pass from the baby along the Umbilical Artery in the unbiblical cord to the Placenta and into the mothers blood so that her body can get rid of it.

THE PLACENTA

Food and Oxygen in

the mothers blood

Waste food and Carbon Dioxide

The Umbilical Cord carries food and Oxygen to the baby and waste away.

Placenta

THE PLACENTA

Placenta

Unfortunately, some harmful substances can pass from the mothers blood into the baby e.g. Alcohol, Drugs, Nicotine and AIDS

THE AMNION

Placenta

This is a bag that surrounds the baby and is filled with a fluid which protects the baby from bumps and bangs.

The Amnion

NINE MONTHS LATER

The baby is ready to be born. The head is engaged - in the right position for birth, at the mouth of the Uterus, the Cervix.

Cervix

Placenta or Afterbirth

Adolescence

When children reach their teens many physical and emotional changes take place which some of them find difficult to come to terms with.

PRIMARY SEXUAL CHARACTERISTICS

Males Females

Secondary Sexual Characteristics

These are changes in the bodies of boys and girls when they are changing from a

boy to man and girl to woman

Physical ChangesPuberty is the period when certain physical changes take place in the male and female body usually in early teens.

Males

• Pubic facial and armpit hair grows

•Voice breaks and deepens

•More muscular body

•Sperm produced by testes.

Females

• Pubic and armpit hair grows

•Breasts develop and body more curved

•Menstrual cycle begins giving her monthly periods