18
Angiosperm Reproduction Chapter 38 2005-2006

Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Embed Size (px)

Citation preview

Page 1: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Angiosperm ReproductionChapter 38

2005-2006

Page 2: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Recall: Alternation of Generations

• In angiosperms:– Sporophyte is dominant– Reduced gametophyte,

dependent on sporophyte

Page 3: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Angiosperm Life Cycle

Page 4: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Gametophytes of Angiosperms

• Male gametophyte– Pollen in anthers of

flower• Female gametophyte– Develops in ovaries of

flower• Seed– Protected in ovary

• Ovary wall can develop into fruit

– Develops into sporophyte

Page 5: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Flowers: Reproductive Organs • Modified shoot

with 4 rings of modified leaves– Sepals– Petals– Stamens• male

– Carpals• female

Page 6: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Male Flower Structure• Stamens = male

reproductive organs– Anther contains

pollen sacs• Pollen sacs produce

pollen• Pollen grain is the

gametophyte (sperm-producing structure)

– Filament stalk supporting anther

Page 7: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Female Flower Structure• Carpels = female

reproductive organs– Ovary at base

• Contains 1 or ovules• Ovules contain embryo

sacs • Embryo sacs are the

female gametophyte (egg-producing structures)

– Style – slender neck connecting ovary to stigma

– Stigma – sticky end of carpel to receive pollen

Page 8: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent
Page 9: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

2005-2006

Page 10: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Fertilization • Pollination– Pollen released from anthers is carried

by wind or animals to land on stigma– Pollen grain produces a pollen tube

• Pollen tube grows down style into ovary & discharges 2 sperm into the embryo sac

• 1 sperm fertilizes egg = zygote• Zygote develops into embryo

– Ovule develops into a seed – Ovary develops into a fruit containing

1 or more seeds

Page 11: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Preventing self-pollination• Various mechanisms

• Stamens & carpels may mature at different times • Arranged so that animal pollinator won’t transfer pollen from

anthers to stigma of same flower• Biochemical self-incompatibility = block pollen tube growth

Page 12: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Fertilization in flowering plants• Double fertilization– 2 sperm from pollen• 1 sperm fertilizes egg =

diploid zygote• 1 sperm fuses with

2 polar nuclei to form 3n endosperm• Endosperm = food

tissue in seed– coconut milk– grains

Page 13: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Plant embryo

endosperm

cotyledons

embryo

seed coat

ovary wall

Page 14: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Fruit • Fruit is a mature ovary

– seeds develop from ovules – wall of ovary thickens to form fruit– fruits protect dormant seeds & aid in their dispersal

Page 15: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Fruit Development• Simple fruit• Ex: peach– 1 flower : 1 carpel : 1 ovary : 1 seed

Page 16: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Fruit Development• Aggregate fruit• Ex: raspberry– 1 flower : many ovaries : many seeds

Page 17: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Fruit Development• Multiple fruit• Ex: pineapple fruit– Many flowers : many carpels : many ovaries :

many seeds

Page 18: Angiosperm Reproduction Chapter 38 2005-2006. Recall: Alternation of Generations In angiosperms: – Sporophyte is dominant – Reduced gametophyte, dependent

Coevolution of Plants & Animals

• Angiosperms & animals have shaped one another’s evolution

• Natural selection reinforced the interactions because they improved the reproductive success of both partners