CHAPTER-1[Reproduction in Organisms]

LIFE-SPAN:- The Period from Birth to natural death.

LIFE-SPAN OF SOME ORGANISMS

1)Elephant = 60-90years
2)rose = 5-7years
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



REPRODUCTION:-  An organisms gives rise to an offspring.
TYPES:- 1)asexual reproduction
               2)sexual reproduction

ASEXUAL REPRODUCTION

Offspring produce by single parents.
Clone:-carbon-copy of single parent [morphologically and genetically similar]

TYPES:-

1.BUDDING [e.g.yeasts]
2.BINARY FISSION [e.g.amoeba]
3.ZOOSPORES [e.g.chlamydomonas]
4.CONIDIA [e.g.penicillium]
5.GEMMULES [e.g.sponge]
6.VEGETATIVE PROPAGATION [runner,rhizome,sucker,tuber,offsets,bulb]
TERROR OF BENGAL:-An aquatic plant "WATER HYACINTH" is the most invasive weeds found in standings water.

SEXUAL REPRODUCTION

Juvenile phase:-Stage of growth and maturity in organisms.
Vegetative phase:-Stage of growth and maturity in plants.

flowering phenomenon:-

1.bamboo = once in lifetime[generally after 50-100yrs]
2.strobilanthus kunthiana [neelakuranji] = once in 12yrs
oestrus cycle :-cyclic changes during reproduction in non-primate animals[such as cows,rats,deers,dogs,etc].
menstrual cycle :-cyclic changes in primates[monkeys,apes and humans]
seasonal breeders :-cycles occurs in favourable seasons in reproductive phase.
continuous breeders :-reproductively active throughout the reproductive phase.

events in sexual reproduction

1.pre-fertilisation events
2.fertilation
3.post-fertilisation events

1)PRE-FERTILISATION EVENTS

a)Gametogenesis:-process of formation of male and female gametes.
     Homogametes(isogametes) :- gametes have same shape,size and structure.
     Heterogametes :- gametes have two morphological distinct types.
     "Male gamete called antherozoid or sperm".
    "Female gamete called egg and ovum".
 BISEXUAL :-having both male and female gamete[1.in  fungi and plants called homothallic and monoecious
                                                                               2.earthworms ,sponge,tapeworm and  leech are                                                                                        bisexual  animals called hermaphrodites].
E.G. OF MONOECIOUS:-CUCURBITS AND COCONUTS
UNISEXUAL :-ON different plants [1. in fungi and plants called heterothallic and dioecious
                                                         2.e.g. cockroach]
E.G. OF DIOECIOUS :-PAPAYA AND DATE-PALM
Male flower called staminate i.e. bearing stamens.
Female flower called pistillate i.e. bearing pistil.
GAMETES are the HAPLOID.

CHROMOSOMES NO. OF SOME ORGANISMS

NAME OF ORGANISM          CHROMOSOMES NO. IN                 CHROMOSOMES

                                                           MEIOCYTES [2N]                      NO.  IN GAMETE [N]

1.HUMAN BEINGS                                       46                                                          23
2.HOUSEFLY                                                12                                                            6
3.RAT                                                             42                                                           21
4.DOG                                                            78                                                          39
5.CAT                                                             38                                                          19
6.FRUIT FLY                                                   8                                                            4
7.OPHIOGLOSSUM[A FERN]                 1260                                                        630
8.APPLE                                                        34                                                          17
9.RICE                                                           24                                                          12
10.MAIZE                                                      20                                                          10
11.POTATO                                                   48                                                           24
12.BUTTERFLY                                           380                                                       190
13.ONION                                                     32                                                         16

B)GAMETE TRANSFER

In organisms, male gametes are motile ; female gamete are stationary but in fungi and algae both are motile.
Gametes are transfer by pollination.

2.FERTILISATION

Fussion of gametes called fertilisation which results in the formation of diploid zygote called syngamy.
PARTHENOGENESIS:-formation of new organism from female gamete without fertilisation.E.g.-rotifers, honeybees,some lizards and bird(turkey).
EXTERNAL FERTILISATION:- SYNGAMY OCCURS OUTSIDE THE BODY.
INTERNAL FERTILISATION:- SYNGAMY OCCURS INSIDE THE BODY.

3. POST FERTILISATION EVENTS
a)the zygote:- in fungi and algae, zygote develops a thick wall i.e. resistant to dessication and damage.
b)embryogenesis:- it refers  to the process of development of embryo from zygote.
OVIPAROUS:-development of zygote, outside the body. E.g.-reptiles and birds
the fertilised egg are covered by hard CALCAROUS SHELL.
VIVIPAROUS:- development of zygote , inside the body E.g.-human beings
IN PLANTS ,zygote develops into embryo, ovules develops into seeds , ovary develops into fruits which develops a thick wall called pericarp i.e. protective in function.