2-Maruza Biosfera. Tabiiy resurslar, ulardan oqilona foydalanish va atmosfera muhofazasi. Suv va Tuproq resurslari va uni muhofazasi. O‘simlik, hayvonot dunyosi va ularni muhofaza qilish

Yo’qolgan turlar 
Hech bir inson dinozavrlarning yo‘q bo‘lib ketish sababini aniq dallillar bilan 
aytibberolmaydi. Bir narsa aniqqi, inson faoliyati va tabiatga ta‘siri dinozavrlardan keyin paydo 
bo‘ldi. Bugun boshqacha hayot. Yo‘qolib borish arafasidagi turlar soni oshmoqda. 1980 yildan 2000 
yilgacha AQSH da 40 ga yaqin o‘simlik va hayvon turlari yo‘q bo‘lib ketdi. Sababi, insoniyatning 
yer yuzini katta maydonlarini egallashi va o‘zlashtirish, ehtiyojlarini qondirishi hisobiga turlar soni 
kamayibketmoqda.
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1
Peter Rillero, Dinah Zike Ecology, 2005. (126-127; 129- bet) 
The Variety of Life 
Imagine walking through a forest ecosystem like the oneshown in 
Figure 1. 
Trees, shrubs, and small 
plants are everywhere.You see and hear squirrels, birds, and insects. You mightnotice a snake or 
mushrooms. Hundreds of species live in thisforest.Now, imagine walking through a wheat field.You 
see onlya few species—wheat plants, insects, and weeds. The forest containsmore species than the 
wheat field does. The forest has ahigher biological diversity, or biodiversity. 
Biodiversity 
refers 
tothe variety of life in an ecosystem.
Measuring Biodiversity
The common measure of biodiversityis the number of species that live in an 
area. For example, acoral reef can be home to thousands of species including corals,fish, algae, 

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sponges, crabs, and worms. A coral reef has greaterbiodiversity than the shallow waters that surround 
it. Beforedeep-sea exploration, scientists thought that few organismscould live in dark, deep-sea 
waters. Although the number oforganisms living there is likely to be less than the number 
oforganisms on a coral reef, we know that the species biodiversityof deep-sea waters is as great as 
that of a coral reef.