UNIT 12 HUMAN POPULATION

-

UNIT 12 HUMAN POPULATION

12.1 HUMAN POPULATION

The number of population is increase over the time. The main cause of population changes is the change in birth rate and death rate. A high birth rate may be caused by early marriages and lack of knowledge of birth control. A high death rate may be caused by diseases, famine, and natural disasters.  

A high birth rate and a low death rate will result in increase in the size of population. 
A low birth rate and a high death rate will result in decrease in the size of population.

Life expectancy may become higher with the improvement in health care and hygiene

12.2 POPULATION DENSITY

Population density refers to the number of people in a given amount of space. When the population grow, the population density will increase. Population density is affected by human migration.

Human migration is movement from one area to another. Human migration may occur in the form of immigration and emigration. Immigration happen when people move into a country permanently. People who do immigration are called immigrant. Immigration will increase the population density. Emigration take place when people move out the country permanently. People who do emigration are called emigrant. Emigration will decrease the population density.

Comments

Post a Comment

Popular posts from this blog

UNIT 7 REPRODUCTION

-
UNIT 7 REPRODUCTION 7.1 Reproduction Living things can produce offspring through asexual and sexual reproduction. Asexual reproduction require one parent. The young produced a clone of the parent. Several asexual reproduction method in animals: Budding, formation of internal buds,  fragmentation, regeneration. Sexual reproduction require two organism: a male and a female. Mature male organism produce reproductive cell called sperm cell . Mature female produce egg . Sperm cell and egg fuse and develop into the young. 7.2 How human life begins Sperm cell meets an egg and fuse. The fusion between male and female reproductive cells is called fertilization . Many sperm cells reach the egg, but only one sperm cell can fertilize the egg. The fertilized egg starts to form more cells. It attaches to the wall of mother womb and continue to develop and grow. The developing baby draws nutrients from mother’s blood through the umbilical cord . About nine month...
Read more

UNIT 9 ECOSYSTEM

-
UNIT 9 ECOSYSTEM 9.1 ECOSYSTEM Ecosystem are all the organisms living together in an area and their interaction with one another as well as their environment. An organism habitat are made up of A biotic (non-living) and B iotic (living) factors. Some A biotic factors are l ight, temperature and air. Sunlight is used by plant to make photosynthesis. The temperature of a habitat determine s the kinds of organisms living there. Plants and animals need oxygen for respiration all the time. Some B iotic factors are man and other animals, plants, bacteria and fungi. Human beings may change the environment through air, land, and water pollution. Animals have to compete with one another for food. Some bacteria and fungi can cause diseases. Plants have to compete with other plants for sunlight, water, and mineral salts from the soils. 9.2 MAKING A MODEL OF ECOSYSTEM 9.3 FACTORS THAT AFFECT THE ORGANISM The amount of sunlight affect the ...
Read more