Let's Know About Human Population!

Before we know about human population, do you know that every 3 minutes babies were born ?
It was true every 3 minutes there are babies born.

The main cause of the human population is the changes in birth rate and death rate. The human population growth is caused by natural increases that occurs when the number of births in the population is more than the number of deaths in the world.  



Birth Rate

The birth rate is the number of live babies are born in a year for every 1000 people. A high birth rate and the low death rate will result in an increase of human population. 


A high birth rate may be caused by :

• .early marriages

• lack of knowledge of birth control

What a very cute baby

Women in early marriages are more likely become pregnant at young age. This increases the likelihood of a young mother producing more children. Lack of knowledge in birth control also leads to more pregnancies. 






















Death Rate

The death rate is the number of people dying in a year for 1000 people. A high death rate and low birth rate will cause the decrease in the size of human population.

A high death rate may be caused by :

• Diseases
• Famine
• Natural Disasters

During a disease outbreak, may people may be in fected and die from the disease. In times of famine , food is scarce and thus , many people may die of starvation. Large numbers of deaths also occurs during natural disasters such as earthquakes &  floods.

 

Because of earthquakes the road is divided into 2

 

These cars are washed up by the floods

Decrease in  population size

A low birth rate together with an ageing population may on the other hand result in a decrease in population size.

A population is considered ageing when : 

• people under age of 15 make up less than 30% of the population.

• people above the age of 65 make up more than 6% of the population

Population Density

Human Population describes its population density. Population density refer to the numbers of people in the given amount of space. When population density  in a place grows , the population density of that place increases. One other factors that affect the population density of a place is migration.

Human Migration 

Human Migration is human movement from one area to another . People who migrate are called migrants. Human migration affects the population size within a certain area but it does not affect the size of the world's human population. Human migration may occur in the form of immigration and emigration.  

Immigration 

Immigration takes place when people move into a country permanently . People who immigrate are called immigrants. A population growth may occur in an area when the amount of immigration more than the amount of emigration. This may cause an increase in the population density of the area.

Emigration

Emigration takes place when people move out of the country permanently, people who emigrate are called emigrants.

Population density decrease as a result of emigration. A population decrease may occur in an area when the amount of emigration exceeds the amount of immigration. This may cause a decrease in the population density of the area.

 

Say No to Pollution !!!!!!!!

At Friday 27th January 2012, I saw a trash that was left at the table in the Canteen At my School. It was a plastic trash. This trash may cause Soil pollution,Water pollution&Air pollution to the Earth. More of Soil pollution will cause many things like soil erosion and many other things. Soil erosion is when trash/rubbish are thrown in the soil and when it rains and the soil will be open and the trash/rubbish will enter and will make a very bad fire. If we cook with that bad fire we will be sick.To stop this trash being thrown anywhere we need to  stop this by making posters of cleanliness in the public places like Canteen ,Malls e.t.c. It can helps us very much to stop pollution.

This picture is telling about Air pollution. The smoke in this car is not really big so you can't see the smoke coming out. This smoke that is coming out from transportation will cause many causes. One of the causes is the burning of fuels,rubbish and forest,dust and dirt in the air , smoke from cigarettes. Air pollution will occurs when harmful substances or pollutants are released in to the air. Usually burning of fuels , rubbish and forest will occurs when pollutants are largely released into the air by vehicles and factories. It is also produces black particles called soot. Usually dust and dirt in the air will occurs when the air we breathe in may appears clean but it may not be free of pollutants. Wind can cause pollutants such as dust and dirt to be suspended in the air.  Smoke from cigarettes consists of harmful substances which pollute the air. The effects of air pollution is health problems,haze and acid rains. The effects of the health problems is when smoke , soot , dust and dirt will cause the eye irritation and it will also damage our respiratory system.Haze is caused by smoke that is released when forests are burnt. It also can cause eye irritation and breathing difficulty.  Smoke released from the burning of fuels contains gases which can dissolve rainwater to form an acid rain.  Acid rain corrodes stones and metals, causing damage to buildings.  It can also harms organisms living in water when it gets into water bodies. Acid rain can also killed plants.

Water pollution occurs when pollutants are released to the water. These pollutants include :

• harmful chemicals from farms and factories.
• Rubbish
• human waste 
• oil spills

Causes of water pollutions

Chemical waste that is produced by factories pollute the water when it is dumped in the water bodies. Water can also polluted when pesticides and fertilisers from farms get washed by the rain into the water bodies. Rubbish is dumped into the water can cause the water to become dirty. the water will also polluted when harmful substances in the rubbish get into the water. Some places do not have a proper way to get rid of urine and faeces. these waste materials are dumped into river,seas,hence polluting the clean water. Oil can be harmful when it leaks from ships into the seas and the oceans causing the oil spills.  The effects of the water pollution is :

Harms Organisms Living In Water

harmful chemical waste contain harmful substances. when these harmful substances released in the water they can poison and kills the organisms living in the water. 


Bacteria grows very fast in the water . They compete with the organisms living in the water.

Harms People 

Polluted water is unsafe if we drink and washing. Diseases can be spread if we drink and use the polluted water. Polluted water can also harm us if we eat animals that lives in the polluted water.