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