Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. It apparently lived in arid regions, and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous. The dicynodonts had two large tusks, extending down from their upper jaws; the tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record, these pig-sized organisms were the most common mammal-like reptiles of the Permian.Which of Lystrosaurusʹ features help explain why these organisms fossilized so abundantly?

I. the presence of hard parts, such as tusks

II. its herbivorous diet

III. its persistence across at least two geological eras

IV. its widespread geographic distribution

V. its mixture of reptilian and mammalian features

#Question id: 11266

#Unit 10. Ecological Principles

Which of the following options lists ecosystems in increasing order of consumption efficiency of herbivore?

#Question id: 11276

#Unit 10. Ecological Principles

Following statement regarding efficiency at different tropic level for secondary production?

A-high production efficiency individual able to survive at little food

B-production efficiency decrease toward increase tropic level 

C-aquatic herbivore is more efficient grazer than terrestrial grazer

D- Carnivore assimilation efficiency appear to average around 10%

Which above combination are correct?

#Question id: 11277

#Unit 10. Ecological Principles

If a species is a keystone predator, then its removal from a community should

(A) Increase population size of the predator’s preferred prey

(B) decrease species diversity in the prey community

(C) decrease productivity of the predator’s preferred prey

(D) increase species diversity in the prey community

#Question id: 11278

#Unit 10. Ecological Principles

Which of the following is true with respect to oligotrophic lakes and eutrophic lakes?

A) Oligotrophic lakes are less subject to oxygen depletion.

B) Rates of photosynthesis are lower in eutrophic lakes.

C) Eutrophic lake water contains higher concentrations of nutrients.

D)Sediments in oligotrophic lakes contain larger amounts of decomposable organic matter.

#Question id: 11279

#Unit 10. Ecological Principles

Ecosystem A: Actual link 10, number of species 15  

Ecosystem B: Actual link 10, number of species 20   

Connectance of ecosystem A and B

#Question id: 11280

#Unit 10. Ecological Principles

Ecosystem services include processes that increase the quality of the abiotic environment. Which of the following processes would fall under this category?