chapter 38: angiosperm reproduction

Question 1

How is a plant cycle characterized?

Answer 1

Alternation between sporophyte (spore-producing) and gametophyte (gamete-producing)

Question 2

What does the angiosperm lifecycle entitle?

Answer 2

1. Flowers
2. Double fertilization
3. Fruits

Question 3

What are flowers?

Answer 3

They are reproductive shoots of angiosperm attached at receptacle.

Question 4

What are the four floral organs?

Answer 4

1. carpels
2. stamens
3. petals
4. sepals

Question 5

What is a pistil?

Answer 5

group of fused carpels

Question 6

What is the anther?

Answer 6

Has pollen sacs that produce pollen

Question 6

What is the difference between a simple pistil and a compound pistil?

Answer 6

simple: unfused carpels
compound: fused carpels

Question 7

What is the difference between complete and incomplete flowers?

Answer 7

complete flowers have all four floral organs while incomplete flowers lack 1 or more organ (usually stamen or carpel)

Question 8

What are a cluster of flowers called?

Answer 8

Inflorescence

Question 9

What is pollination?

Answer 9

transfer of pollen from an anther to a stigma.
When landed, pollen grain produces pollen tube, grows down to ovary and discharges two sperm cells.

Question 10

What are the main methods of pollination?

Answer 10

1. Animals (bees- 65% of all flowering plants are pollinated by insects)
2. Wind (abiotic pollination (20% of angiosperms)
3. Water

Question 11

What is coevolution?

Answer 11

Joint evolution of interacting species in response to selection imposed by each other.

Question 12

What is the male gametophytes mechanism?

Answer 12

1. pollen develops from microspore in microsporangia (pollen sac)
2. microspore undergoes mitosis, producing
   i. generative cell
   ii. tube cell

Question 13

What is the female gametophytes mechanism?

Answer 13

1. embryo sac develops within ovule
2. In an ovule, 2 integuments surrond a megasporangium
3. One cell undergoes meiosis, producing 4 megaspores, where only 1 survives
4. Megaspore divides without cytokinesis, producing 1 large cell with 8 nuclei
5. This cell is partitioned into embryo sac

Question 14

What does a pollen grain consist of?

Answer 14

two-celled male gametophytes and spore wall

Question 15

What is fertilization

Answer 15

fusion of gametes occurs after the two sperm reach female gametophyte

Question 16

What is an endosperm?

Answer 16

One sperm fertilizes the egg and the other combines with the two polar nuclei

Question 17

Why is double fertilization crutial?

Answer 17

Ensures endosperm only develops in ovules containing fertilized eggs

Question 18

What happens after double fertilization?

Answer 18

each ovule develops into a seed

Question 19

What does the ovary develop into?

Answer 19

A fruit, enclosing the seeds

Question 20

What happens when seed germinates?

Answer 20

Embryo develops into a new sporophyte

Question 21

How does endosperm development happen?

Answer 21

It precedes embryo development, stores nutrients used by seedling.

Question 22

What happens during embryo development?

Answer 22

the first miotic division of zygote splits fertilized egg into
1. basal cell: that produces multicellular suspensor (anchors embryo to parent plant)

2. terminal cell: gives rise to most of embryo

Question 23

What is the structure of a mature seed?

Answer 23

embryo and food supply enclosed by hard protective seed coat, with cotyledon inside

Question 24

What is a cotyledon?

Answer 24

seed leaf that retains food in their endosperm and absorb nutrients from endosperm to transfer during germination. monocots: have 1 cotyledon eudicots: have 2 cotyledons

Question 25

What is the embryonic axis called?

Answer 25

hypocotyl and it terminates in the radicle.

Question 26

What is a scutellum?

Answer 26

special cotyledon in grasses (maize and wheat)

Question 27

Why is seed dormancy important?

Answer 27

It increases the chances germination occurs at a time/place most advantageous to seedling.

Question 28

What breaks seed dormancy?

Answer 28

Environmental cues, like temperature changes and lighting changes

Question 29

What does germination depend on?

Answer 29

Inhibition, which is the uptake of water due to low water potential of a dry seed.

Question 30

What is the seeding development of the eudicot seed germination?

Answer 30

1. the hook forms in hypocotyl the growth then pushes hook above ground. 2. light causes hook to straighten, pulling cotyledons and shoot tip up.

Question 31

What is the seeding development of the monocot seed germination?

Answer 31

1. coleoptile pushes through soil, creating tunnel for shoot tip.

Question 32

What is the development of flowering?

Answer 32

1. germinated seed starts to photosynthesize 2. resources are devoted to stem, leaves and roots 3. flowers are synchronized to appear to promote outbreeding by environmental cues and internal signals.

Question 33

What is a fruit?

Answer 33

mature ovary of a flower It protects enclosed seeds and helps seed dispersal

Question 34

What are the 4 different types of fruits?

Answer 34

1. Simple fruits: develop from single/several fused carpels ex: pea flower and pea fruit 2. Aggregate fruits: result from single flower with multiple separate carpels ex: raspberry flower and fruit 3. Multiple fruits: develop from a group of flowers called an inflorescence ex: pineapple inflorescence and fruit 4. Accessory fruits: contains other floral parts in addition to ovaries ex: apple flower and fruit

Question 35

What are the two types of reproduction?

Answer 35

1. sexual reproduction: offspring that are genetically different from parents 2. asexual reproduction: results in clone of genetically identical organisms.

Question 36

What is fragmentation?

Answer 36

The seperation of parent plant into parts that develop into whole plants

Question 37

What is apomixis?

Answer 37

asexual production of seeds from a diploid cell (without fertilization)

Question 38

What are the advantages and disadvantages of asexual reproduction?

Answer 38

Advantages: 1. vegetative reproduction: progeny arises from mature vegetative fragments. 2. stable environment, gives a beneficial and successful asexual reproduction. Disadvantages: 1. environmental change causes vulnerability of a clone of plants to local extinction.

Question 39

What are the advantages and disadvantages of sexual reproduction?

Answer 39

Advantages: 1. generates genetic variation making evolutionary adaptation possible 2. some flowers self-fertilize; ensuring every ovule will develop into a seed 3. mechanisms evolved to prevent selfing Disadvantages: 1. only fraction of seedlings survive

Question 40

What are the mechanisms that prevent self-fertilization?

Answer 40

1. Dioecious species have staminate and carpellate flowers on separate plants. 2. Some arrange so that stamen and carpels mature at different times 3. Self-incompatibility: plants ability to reject its own pollen. (recognition of self blocks pollen tube growth.