Exercise 2

Question 1 :

Normal adult human male has


A). 10 gram of haemoglobin/100 gram of blood
B). 14 gram of haemoglobin/100 gram of blood
C). 18 gram of haemoglobin/100 gram of blood
D). 24 gram of haemoglobin/100 gram of blood
Answer : Option B

Question 2 :

Plants wilt due to excess of


A). transpiration
B). photosynthesis
C). absorption
D). None of these
Answer : Option A

Question 3 :

Monotremes are unique mammals because they


A). posses hair
B). give birth to live young
C). secret milk in a pouch
D). lay eggs
Answer : Option D

Question 4 :

Poison glands of snakes are homologous to


A). electric organs of fishes
B). stings of rays
C). sebaceous glands of mammals
D). salivary glands of vertebrates
Answer : Option D

Question 5 :

Radical vascular bundles are those in which


A). xylem is surrounded by phloem
B). phloem is surrounded by xylem
C). xylem and phloem occur on the same radius
D). xylem and phloem occur on the different radii
Answer : Option D

Explanation :

With the help of examples, explain the various types of vascular bundles.

In angiosperms the vascular bundles are mainly of three types (i) radial (ii) conjoint (iii) concentric.

(i) Radial : Presence of radial vascular bundles is the characteristic feature of roots. Those vascular bundles in which xylem and phloem are present on different radii are known as radial vascular bundles. In between xylem and phloem bundles parenchymatous cells are present.

(ii) Conjoint : In these vascular bundles xylem and phloem are present on the same radii. Conjoint vascular bundles may be collateral (phloem is present only outer to xylem) or bicollateral (phloem is present on both sides of xylem). If cambium is present between xylem and phloem then the vascular bundle is known as open, otherwise it is called closed.

(iii) Concentric : Those vascular bundles in which one type of vascular tissue is surrounded by another type are known as concentric vascular bundles. These bundles may be amphivasal or leptocentric(phloem is completely surrounded by xylem) or amphicribal or hardocentric (xylem is completely surrounded by phloem). Amphivasal bundles are found in Dracaena and Yucca. Amphicribal bundles are found in stamens of many dicots etc.