Bio Packet 1, Exam 4

Plant reproduction

All land plants have __________

alternation of generations

Gymnosperms

• “Naked seeds” have no fruit or flower

• Usually wind dispersal

• Examples include pine cones

Angiosperms

Plants that produce flower and fruit

Plants can reproduce

sexually and asexually

Advantages of Asexual Reproduction

• Efficient

• Increases individual genetic output

Advantages of Sexual Reproduction

• Meiosis and outcrossing increases genetic diversity

A flower is ______

a specialized shoot with 4 layers of modified leaves

Perfect Flower

Flower with male and female parts and 4 whorls

Imperfect flower

Flower with only male or female parts but not both

Flower Structure: Male Parts

Stamen:

• Anther

• Filament

Flower Structure: Female Parts

Carpel:

• Stigma

• Style

• Ovary

Flower Structure misc. parts

• Petals

• Ovule

• Receptacle

• Sepal

The production of the male pollen grain occurs in the ______

anther

Female gametophyte (1n) has only ____ cells

7

Spores go through mitosis to create gametophytes in both ______ and _____

male and female parts

Male gametophyte on has ___ cells

2-3 cells

The sporophyte is the _____

outer coat

Male gametophyte (1n) is made up of the

Generative and tube cell

Non-Seed

Sperm swims to egg

Seed

Pollen transferred by wind or animals

How is pollen advantageous for life on land?

• Protects sperm

• No water required

• Colonize new dry places

• Pollen can live for a long time

Gymnosperms primarily use _____ pollination

wind pollination but it can be inefficient

Mutualism

• Mutually beneficial

• Ex: Animals eat pollen and nectar and plants get precise pollination

Sexual Deception

Mimic insects’ appearance and pheromones

Some attract male insects to land on flower and distribute pollen

Wind-pollinated:

• Scentless

• No nectar

• Not colorful

• Ex: corn is pollinated this way

Flower attributes target specific pollinators

Same flower may smell different in different habitats to attract bees or flies

Coevolution

rapid selection due to reproductive isolation

Pollination

Delivery of pollen (1n) from anther to stigma

Fertilization

joining of sperm and egg to form diploid zygote

Pollination and fertilization process:

• Generative cell divides to make 2 sperm

• Sperm swim down tube (style) to ovary

• Multiple pollen tubes can fertilize multiple ovules in a single ovary

Double fertilization Steps:

1. Pollen grain lands on stigma

2. Pollen tube grows down style

3. Generative cell divides into 2 sperm in pollen tube

4. Pollen tube and sperm reach ovule/egg

Double fertilization basics:

• 1 sperm fertilizes egg makes a zygote

• 1 sperm fertilizes 2 other nuclei to make 3n endosperm

Seed coat and embryo are __________

genetically identical

seed coat is all from female sporophyte (2n)

Endosperm make up

2n from mom

1n from dad

to make 3n

Seed

• Ultimate survival structure for land because:

  • food supply (endosperm)

  • thick outer seed coat

  • can have dispersal mechanisms

Dispersal by Spore vs Seed

Same:

• Durable

• Disperse

• Reproductive structures

Different:

• Spore is uni- or bicellular; seed is multicellular, complex

• Spore is haploid; seed is multi-generational

Endosperm in Eudicot vs Monocot

Eudicot:

• 2 cotyledons, cotyledons store carbs (starch)

Monocot:

• 1 cotyledon, endosperm stores carbs (starch)

Fruit is _______

a ripened ovary

ovules become seeds

Seeds and fruits are good dispersal agents

Why disperse?

• Escape deteriorating environment

• Avoid competition

• Avoid inbreeding

Radicle

first to emerge (embryonic root)

Hook or coleoptile

protect emerging shoot

Cotyledons or endosperm

feed heterotrophic seedling

Germination depends on ______

water uptake

Dispersal delivers ____

diploid cells