(i) Population growth:
Population growth refers to an increase in the number of people who reside in a particular area during a particular period.
(iii) Census:
It is an official enumeration of population carried out periodically, It records information about the characteristics of population such as age, sex, literacy and occupation.
(iii) Sustainable Development:
1. The excessive usage of natural and manmade resources deplete its availability for the future generation.
2. We need to look after our planet, our resources and our people to ensure that we can hand over our planet to our children to live in true sustainability.

(i) Saplings of native species of plants and trees are being grown planet and cared for
(ii) Live colonies of coral from the Gulf of Mannar Biosphere Reserve are being transplanted to Palk Bay. The existing mangroves and the region are being mapped and the way land is used around the mangrove is being studied.
(iii) Along with awareness programmes, the communities are also being provided with livelihood training, so they can earn an income in more ways than just fishing.

(i) Areas of high density (above 50 people per sq.km) - East Asia, South Asia, North West Europe and Eastern North America.
(ii) Areas of low density (less than 10 people per sq.km) - Central Africa, Western Australia, Northern Russia, Canada, etc.

(i) Natural Disaster or man made disaster such as famine, war, land slides, earthquake, Tsunami, epidemics, extreme weather, etc.
(ii) The black death is estimated to have killed 30 - 60 percent of Europe's total population during the 14^th century.
(iii) The dominant explanation for black death is attributed to the break of plague.

(i) Density of population refers to the number of people living per sq. km.
(ii) An area is said to be sparsely populated when it has large area with less number of people.
(iii) Similarity, smaller the area with a targe number of people. it is said to be densely populated.
(iv) Population density = \(\frac{Total \ population}{Total \ land \ area}\)