Plant Diversity II

Question 1

reduced gametophyte

Answer 1

• microscopic
• developed inside cones/flowers
• dependent on sporophyte
• protects gametophyte from environment
• ensures nutrients for gametophyte

Question 2

heterospory

Answer 2

production of 2 different types of spores

• megaspore grows into megagametophyte
• microspore grows into microgametophyte

Question 3

ovule

Answer 3

megaspore + megasporangium + integuments

Question 4

integuments

Answer 4

protective sporophyte tissue around megasporangium, form seed coat

Question 5

pollen grain

Answer 5

male gametophyte within pollen wall (with sporopollenin)

• develops from microspore
• male gametophyte - 2 cells
• tube and generative cell

Question 6

tube cell

Answer 6

germinates and produces pollen tube

Question 7

generative cell

Answer 7

produces sperm; eventually divides into 2 sperm cells

Question 8

pollenation

Answer 8

• transfer of pollen to part of plant containing ovules
• by wind or animals
• NOT fertilization

Question 9

what is the significance of pollenation?

Answer 9

sperm dispersal not water dependent (more lack flagella)

-can colonize dry habitats

Question 10

how is pollen grain formed?

Answer 10

microsporangium -> meiosis -> microspores -> mitosis -> microgametophyte -> pollen grain

Question 11

how does the pollen grain reach the ovule?

Answer 11

wind

Question 12

what happens in the megasporangium in the pine life cycle?

Answer 12

megasporocyte -> meiosis -> megaspore -> mitosis -> megagametophyte -> 2-3 archegonia

Question 13

what happens when the pollen tube reaches the archegonium

Answer 13

• sperm cells have developed from generative cell
• fertilization -> zygote
• usually occurs > a year after pollenation

Question 14

what are the products when an ovule becomes a seed>

Answer 14

consists of embryo (immature sporophyte), food supply, and seed coat

Question 15

what are the earliest seed plants?

Answer 15

gymnosperms

Question 16

flowers

Answer 16

structure specialized for sexual reproduction

Question 17

fruits

Answer 17

• ovary wall thickens, matures into fruits as seeds develop
• protects seed
• facilitates dispersal
• many mechanisms (wind, water, animals)

Question 18

pollination in angiosperm cycle

Answer 18

• pollen released from stamen, carried to carpel
• some flowers self-pollinate
• most have mechanisms to ensure cross-pollination
• pollen grain absorbs water, germinates
• tube cell produces pollen tube
• ovule through micropyle: pore in integument
• 2 sperm cells enter female gametophyte

Question 19

what does the ovary become in angiosperms?

Answer 19

fruit

Question 20

what does the ovule become in angiosperms

Answer 20

seed

Question 21

angiosperm diversity

Answer 21

• single phylum - Anthophyta - “flower plants”
• ~250 K species - 90% of known plants
• most diverse and widespread plants