(a) Write the specific location and the functions of the following cells in human males:
(i) Leydig cells
(ii) Sertoli cells
(iii) Primary spermatocyte
(b) Explain the role of any two accessory glands in human male reproductive system.
(a) Name the primates that lived about 15 million years ago. List their characteristic features.
(b) (i) Where was the first man-like animal found?
(ii) Write the order in which Neanderthals, Homo habilis and Homo erectusappeared on earth.
State the brain capacity of each one of them.
(iii) When did modern Homo sapiens appear on this planet?
(a) Explain primary productivity and the factors that influence it.
(b) Describe how do oxygen and chemical composition of detritus control decomposition?
(a) What is El Nino effect? Explain how it accounts for biodiversity loss.
(b) Explain any three measures that you as an individual would take, to reduce environmental pollution.
(a) An El Nino event is a temporary change in the temperature, surface air pressure and currents of the Pacific Ocean in the region surrounding the equator. It affects both the ocean and atmosphere and can have major effects on the world's climate. El Nino causes global warming and the melting of polar ice cap. This leads to the submerging of coastal regions and loss of species endemic to that area. As El Nino also affects the ocean currents and causes sudden cooling or warming of the oceans, it leads to the death of marine life such as coral reefs and fishes as well. The depletion of coral reefs, in turn affects the life of other marine organisms that depend on the coral reefs for food and shelter.
(b) The measures that we as an individual can take in order to reduce environmental pollution can be
(i) Dumping of organic waste in places far from residential areas.
(ii) Using car pool so as to reduce pollution and fuel consumption.
(iii) Turning off air conditioners when not in use.
(iv) Planting more and more trees and reducing the deforestation.