sexual reproduction Archives - Free ZIMSEC & Cambridge Revision Notes

Effects of population growth on natural resources

By garikaib|2022-09-15T12:37:48+02:00September 7th, 2016|Notes, O Level Science Notes, Ordinary Level Notes|

Environmental degradation in Epworth. Image credit newsday.co.zw

Environmental degradation in Epworth. Image credit newsday.co.zw ZIMSEC O Level Combined Science Notes: Population and natural resources

Environmental Effects

Soil erosion
Deforestation
Desertification
Reduced soil fertility

Social Effects

Overcrowding
Criminal activities
Immorality
Poor health services
Poor education facilities
General increase in poverty

To […]

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Population Dynamics

By garikaib|2022-09-15T12:37:48+02:00September 7th, 2016|Notes, O Level Science Notes, Ordinary Level Notes|

Image credit idealscounseling.org

Image credit idealscounseling.orgZIMSEC O Level Combined Science Notes: Population Dynamics

Population-all the inhabitants of a particular place/area at one given time
The study of changes in population is known as demograph

Factors affecting population change

The birth rate-the number of live births per 1000 people per year.
Death/Mortality rate-is the number of […]
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Sexually Transmitted Infections (STIs)

By garikaib|2022-09-15T12:37:49+02:00September 7th, 2016|Notes, O Level Science Notes, Ordinary Level Notes|

Image credit singleblackmale.org

Image credit singleblackmale.org ZIMSEC O Level Combined Science Notes: Sexually Transmitted Infections (STIs)

To access more topics go to the Combined Science Notes page

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Causes of infertility

By garikaib|2022-09-15T12:37:49+02:00September 7th, 2016|Notes, O Level Science Notes, Ordinary Level Notes|

Sterility can cause strain in a relationship. Image credit colossiansfamilynetwork.org

Sterility can cause strain in a relationship. Image credit colossiansfamilynetwork.org ZIMSEC O Level Combined Science Notes: Causes of infertility

Sterility is the inability to reproduce
There are a number of causes for sterility
Low sperm count (makes it […]
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Contraception:Ways to prevent pregnancy

By garikaib|2022-09-15T12:37:50+02:00September 6th, 2016|Notes, O Level Science Notes, Ordinary Level Notes|

There are several major methods of contraception. Image credit relationshipplaybook.com

There are several major methods of contraception. Image credit relationshipplaybook.com ZIMSEC O Level Combined Science Notes:Contraception:Ways to prevent pregnancy

Contraception-the deliberate use of artificial methods or other techniques to prevent pregnancy as a consequence of sexual intercourse
Common methods of contraception […]
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Contraception: Abstinence

By garikaib|2022-09-15T12:37:50+02:00September 6th, 2016|Notes, O Level Science Notes, Ordinary Level Notes|

Couple holding hands. Image credit neguswhoread.com

Couple holding hands. Image credit neguswhoread.com ZIMSEC O Level Combined Science Notes:Contraception: Abstinence

It involves total avoidance of sexual intercourse

Adavantages

Many couples agree to wait until marriage
There is no risk of contracting Sexually Transmitted Infections
It is 100% effective
It is supported by most religious […]
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Contraception: Sterilisation

By garikaib|2022-09-15T12:37:51+02:00September 6th, 2016|Notes, O Level Science Notes, Ordinary Level Notes|

Black couple. Image credit blackcouplegetaways.com

Black couple. Image credit blackcouplegetaways.com ZIMSEC O Level Combined Science Notes:Contraception:Ways to prevent pregnancy

How it works

Can be done in both men and women
In men it is known as a vasectomy
- Sperm duct is cut and tied
- During sexual intercourse ejaculated fluid contains no sperm

[…]

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Contraception: Loop/IUD (intrauterine device)

By garikaib|2022-09-15T12:37:51+02:00September 6th, 2016|Notes, O Level Science Notes, Ordinary Level Notes|

Black couple. Image credit classic105.com

Black couple. Image credit classic105.com ZIMSEC O Level Combined Science Notes:Contraception:Ways to prevent pregnancy

How it works IUD

IUD

Is a small copper/plastic device placed inside the uterus
It prevents the embryo from implanting in the uterus
by […]
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