IGCSE Biology Paper-1: Specimen Questions with Answers 114 - 115 of 208

Question 114

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Question

MCQ▾

Which diagram shows one organ only?

The Photosynthetic

The Photosynthetic

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Choices

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

Answer

a.

Explanation

The leaf is a green and main photosynthetic organ of a green plant, flat, thin, expanded lateral appendage of stem which is borne at a node and bears a bud in its axil. It is exogenous in origin and develops from the leaf primordium of shoot apex. The green colour of leaf is due to presence of the photosynthetic pigment – chlorophyll which helps plants to synthesize organic food. The green photosynthetic leaves of a plant are collectively called foliage. They are borne on stem in acropetal succession.

It is Exogenous in Origin

It is Exogenous in Origin

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Question 115

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Question

MCQ▾

The cross section of a trunk of tree shows 50 annual rings, the age of tree is

Choices

Choice (4)
a.25 years
b.50 months
c.100 years
d.50 years

Answer

d.

Explanation

  • Annual rings are bands of secondary xylem and xylem rays. Each annual ring shows the growth of one year. Thus, by counting the number of annual rings, at the base of main stem of plant we can calculate the age of the plant. This branch of science is called dendrochronology. Now a days increment borer, an apparatus is used to calculate the annual rings.
  • In tropical regions, the cambium is equally active throughout the year, thus there is no distinction like spring & autumn wood. The whole wood consists of uniform xylem elements; thus, no annual rings are found.
  • More distinct annual rings are formed in temperate deciduous plants. In deserts annual rings are less distinct.
A Dendrochronology

A Dendrochronology

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