Fertilization

[Fertilization]

Explain the 3 prefertilization events

1)Pollen germination

2)Pollen tube Growth

3)Division of generative nucleus

Explain the prefertilizatiin events

1)Pollen grain germinated on stigma forming Pollen tube

2)Pollen tube germinated through style towards ovary

3)Generative nucleus divides mitoticaly forming 2 sperms

[Entry in the ovule]

Explain the 2 parts in the (entry into ovule)

1)Pathway

*Pollen tube enters ovary through micropyle(pore of integuments in ovule)

2)Discharge

*2 sperms release into embryo sac

[Fusion Events-Double fertilization]

Define Double fertilization(2)

The occurrence of

1)sperm fuses with egg to form diploid zygote

&

2)Other sperm fuses with 2 polar nuclei

State a special fact about double fertilization

Unique to Angiosperms

[Post Fertilization Development]

Explain 3 points

1)Embryo formation

*Zygote develop to Embryo

2)Endosperm formation

*Triploid nucleus develop to Endosperm

(Store food)

3)Synchronisation significance

*Ensures simultaneous develop of Embryo and endosperm

*Prevent wastage of nutrients on infertile ovules(Fertilization doesn’t occur)

[Seed formation]

State the components of seed and explain function of 1 of them

1)Embryo

2)Endosperm (Store food)

3)Seed coat

What is the encasement of seed

Seeds are enclosed by fruit

[Fruit development]

Define fruit

Enlarged & developed ovary

State the 3 steps of fruit formation

1)Origin & stimulation

*Fruit develops from ovary after fertilization

*Fertilization triggers Hormonal changes that cause ovary to form fruit

2)Pericarp formation

*Ovary wall differentiates into pericarp

3)condition when pollination fails

*No pollination or fertilization→No fruit development

*entire flower falls off

[Parthenocarpy]

Definition

Development of fruit directly from ovary without fertilization(occurs in some plants)

Key features

1)Parthecarpic fruits don’t develop seeds

2)Natural occurrence

*Naturally occurs in some species

(Eg-Banana)

3)Artificial induction

*Archeived bi inducing plant growth substances to get seedless fruits

Eg-Grapes,Orange)

[Parthenogenesis]

Define

Formation of seeds without fertilization

(Some plants)

Eg-Certain grasses

State 3 key characteristics of parthenogenesis

1)Egg is resulted from mitosis(hence 2n)

2)Haploid ovum fuses with polar nucleus

3)Genetic content of the egg is duplicated to become 2n

*Enables seed development without fertilization