Lecture 13 - Plants

Question 1

What is a seed

Answer 1

• > an embryonic plant enclosed in a protective outer covering
• > also stored food

Question 2

Advantages of seeds

Answer 2

• > seed dispersal through time / waiting until the conditions are just right
• > gametophyte reduction

Question 3

what is gametophyte reduction

Answer 3

• > sporophytes evolved innovations for dry environments, gametophytes did not
• > gametophytes reduced and dependent on sporophyte

* protect from desiccation and UV radiation, provide nutrients

• > gametophyte has been reduced from being essentially what we would consider to be the plant to being a few measly (but still vitally important) cells.

Question 4

gametophyte vs sporophyte

Answer 4

Question 5

Homospory vs Heterospory

Answer 5

Homospory refers to the production of a single kind of spore, neither microspore nor megaspore, while heterospory refers to the production of two types of spores differing in size and sex, the male microspore and the female megaspore.

Question 6

Gymnosperm

Answer 6

“Naked” seeds (not enclosed in ovaries)

• > sporophylls (modified leaves bearing sporangia) typically clustered to form cones

Question 7

Microspore production

Answer 7

pollen cone = cluster of microsporophylls

• > microsporocytes produce four haploid microspores
• > microspores mature as pollen grains - two celled male gametophyte in sporopollenin wall

Question 8

List the major classes of gymnosperms

Answer 8

• > cycadophyta
• > gnetphyta
• > ginkgophyta
• > coniferophyta

Question 9

Angiosperms

Answer 9

• > produce flowers and seeds in fruits (seeds enclosed in mature ovaries)

Question 10

how did the angiosperm group become so diverse

Answer 10

angiosperms have a huge amount of stomata (plural of stoma; let CO₂ in the plant) and veins which really makes the most of their photosynthesis. These stomata bring in loads of CO2 and the veins move sugars around very easily. This has helped angiosperms grow and spread way faster than other plants and has pretty much led them to world domination!

Question 11

Angiosperms vs Gymnosperms

Answer 11

Question 12

Flowers and their structures

Answer 12

has special structure for sexual reproduction

Sepals: protect developing flowers

Petals: help attract pollinators

Stamens: modified microsporophylls (filaments and anthers)

Carpel: modified macrosporophylls (stigma, style and ovary)

Question 13

What are fruits

Answer 13

fertilized ovules mature into seeds surrounding ovary develops into fruit

• > protects developing/dormant seeds and aids dispersal