Question

What is exclusive for angiosperms?
A. Vessels
B. Secondary growth
C. Double fertilization
D. Autotrophic nature

Answer 1

We are familiar with the word Angiosperm i.e. a plant that produces flowers and it belongs to one of the vital groups of plants having seeds. This word is derived from the Greek word where angeion stands for vessel and sperma stands for seed. Angiosperm is divided into two groups 1. Monocot and 2. Dicot based on the number of cotyledons.

Complete answer:
Here, option (a) Vessels- They are not present in all the angiosperms so it is not considered a universal feature of angiosperms. Angiosperms which lack vessels are: Wintera, Trochodendron, etc. Vessel is also known as trachea and it is found in xylem which is water conducting tissue of the plants.
Option (b) Secondary growth- It increases the diameter of root and stem of the plant by forming secondary tissue. It occurs in dicots and in gymnosperm but in monocots the primary plant body is complete in itself.
Option (c) Double fertilization- It is the characteristic feature of angiosperm and in this process formation of both diploid zygote and triploid endosperm takes place. It involves two sperm cells from which one fertilizes the egg cell and forms zygote this is known as syngamy and another one fuses with two polar nuclei and forms the endosperm and this is known as triple fusion. Thus, both syngamy and triple fusion together are known as Double fertilization.
Option (d) Autotrophic nature- They are those which synthesize their food themselves by photosynthesis process; but angiosperms have heterotrophic mode of nutrition.

Hence, the correct answer is option (c) i.e. Double fertilization as it is known as the universal feature of angiosperms.

Note: Angiosperms do not prepare their food by the process of photosynthesis as they have heterotrophic mode of nutrition. Double fertilization involves the combination of a female gametophyte with two male gametophytes. Secondary growth does not occur in monocots but it occurs in dicots of angiosperm.