Dr. Prasant Kumar

The period from birth to the natural death of an organism represents its lifespan. Every organism has a specific average lifespan. It means every organism grows and lives for a particular length of time. Lifespan varies based on the organism.

Lifespan depends upon four stages:

(i) Juvenility: Represents the stage when organism develops the capacity to reproduce.

(ii) Maturity: Stage when reproduction starts.

(iii) Aging and senescence: Progressive deterioration in body of a living being is called aging. The irreversible stage of ageing is known as senescence.

(iv) Death: In death, there is permanent cessation of all vital activities.

Life-Span of some Organisms:

1) Elephant = 60-90years

2) Human = 75-85years

3) Dog = 20-50years

4) Butterfly = 1-2weeks

5) Crow = 15years

6) Banana tree = 25years

7) Cow = 20-25years

8) Parrot = 140years

9) Crocodile = 60years

10) Horse = 60years

11) Fruit fly = 30days

12) Rice plant = 3-4months

13) Tortoise = 100-150years

14) Banyan tree = 200years.

i. Embryo with two cotyledons.

ii. Pollen with three furrows or pores.

iii. Flower parts in multiples of four or five.

iv. Majority of time leaf veins are reticulated.

v. Stem vascular bundles are in the form of a ring.

vi. Roots develop from radical.

vii. Secondary growth observed in Dicots.

Alleles are the pairs of genes occupying a specific spot called locus on a chromosome. Typically, there are only two alleles for a gene in a diploid organism. When there is a gene existing in more than two allelic forms this condition is referred as multiple alleles.

Example: ABO blood groups system in humans.