IGCSE Biology Paper-1: Specimen Questions with Answers 204 - 205 of 208

Question 204

Edit

Question

MCQ▾

The diagram shows how a new population may grow over time.

At which point there is great fall in the number of individuals in the given population?

Population Size Graph

Population Size Graph

Loading image

Choices

Choice (4)
a.C
b.D
c.B
d.A

Answer

b.

Explanation

When resources like food and space etc. in a habitat are unlimited, each species realizes its full reproductive or biotic potential and grows in an exponential or geometric fashion. For example, if a reindeer population can grow in a predator free environment, the population in time grows beyond carrying capacity and forms ‘J’ shaped growth pattern/curve. Such growth also occurs in algal bloom, insects during rainy season and Paramecium (doubling every day). Thus, under unlimited resources and absence of check any species can grow exponentially. Even the slowest breeder, elephant (gestation period –22 months) can grow to enormous number but as there is exponential rise it continues with great fall in their numbers and a huge number of organisms dies also.

Question 205

Edit

Question

MCQ▾

The diagram below is showing a special muscular movement.

Wall of Gullet

Wall of Gullet

Loading image

What will be the process?

Choices

Choice (4)
a.Peristalsis movement
b.Digestion
c.Flapping movement
d.Rotatory movement

Answer

a.

Explanation

The alimentary canal has layers of muscle in its walls. The fiber of one layer of muscles run around the canal (circular muscle) and the others run along its length (longitudinal muscle). When the circular muscles in one region contract, they make the alimentary canal narrow in that region. A contraction in one region of the alimentary canal is followed by another contraction just below it so that a wave of contraction passes along the canal, pushing food in front of it. The wave of contraction, called peristalsis.