Lecture 15 & 16 Seed Plants, Angiosperms

Question 1

what is the one phylum in angiosperms?

Answer 1

anthophyta - includes smallest and tallest seed plants

Question 2

what is the angiosperm life cycle?

Answer 2

• AoG - sporophyte is dominant - gametophyte is reduced in size / microscopic and depend on the sporophytes for nutrients

Question 3

what are the the “three Fs” of the angiosperm life cycle?

Answer 3

• Flowers - double Fertilization - Fruits

Question 4

what are flowers?

Answer 4

• specialized reproductive shoots of angiosperm sporophytes

Question 5

how do flowers attatch to the stem?

Answer 5

• via receptacle

Question 6

what are the four floral organs?

Answer 6

• sepals + petals + stamens + carpels

Question 7

what are the four reproductive floral organs?

Answer 7

• stamens and carpels (sepals and petals are sterile)

Question 8

what are stamen?

Answer 8

• microsporophyll that consist of stalk / filaments topped by an anther with pollen sacs that produce pollen

Question 9

what are carpels?

Answer 9

• megasporophyll that consist of ovary at the base and style leading up to stigma where pollen is received

Question 10

what are incomplete/complete flowers?

Answer 10

• complete have all 4 organs - incomplete lack one or more

Question 11

what are clusters of flowers called?

Answer 11

• inflorescences - ex: sunflower

Question 12

what is the development of male gametophytes in angiosperms?

Answer 12

• pollen grain is 2-celled male gametophyte and spore wall - pollen develops from microspores within the microsporangia (pollen sacs) of anthers - each microspore undergoes mitosis to produce two-celled gametophytes: generative cell (sperm) + tube cell (pollen tube)

Question 13

what is the development of female gametophytes in angiosperms?

Answer 13

• female gametophyte or embryo sac develops within ovule contained within ovary at stigma base - within an ovule, two integuments surround megasporangium - one cell in megasporangium undergoes meiosis - 4 megaspores but only one survives - megaspore divides producing 7-celled fem gametophyte (gymno have ~3k) - large central cell has 2 nuclei POLAR NUCLEI

Question 14

what is STEP 1 of angiosperm life cycle?

Answer 14

FLOWERS - POLLINATION - pollen grain produces pollen tube - generative cell undergoes MITOSIS to produce two sperm cells - pollen tube grows into ovary and discharges two sperm cells

Question 15

what is STEP 2 of angiosperm life cycle?

Answer 15

• DOUBLE FERTILIZATION - pollen tube discharges two sperm into embryo sac within ovule - one sperm fertilizes egg –> zygote (2n) - other sperm consumes with polar nuclei giving rise to the TRIPLOID (3n) food storing ENDOSPERM – nourishes developing embryo

Question 16

what is STEP 3 of angiosperm life cycle?

Answer 16

FRUIT - SEED DEVELOPMENT - each ovule develops into a seed - ovary develops into a fruit enclosing the seed

Question 17

what does the triploid endosperm do?

Answer 17

• nutrients for embryo - repeatedly undergoes mitosis to produce starchy food for embryo - in most monocots and some eudicots, stores nutrients - in other eudicots food reserves of endosperm exported to cotyledons

Question 18

what is embryo development?

Answer 18

• first mitotic division - splits egg into basal and terminal cell - basal cell produces multicellular suspensor which anchors embryo to parent plant - terminal cell gives rise to most of embryo - cotyledons form & embryo elongates

Question 19

what are 2 types of fruit?

Answer 19

• dry or fleshy

Question 20

what are the three classifications of fruit based on their development?

Answer 20

• aggregate: single flower with multiple separate carpels ex raspberry - simple: singer or several fused carpels ex peas - multiple: group of flowers called an inflorescence ex: pineapple

Question 21

what is an accessory fruit?

Answer 21

• contains other floral parts in addition to ovaries?

Question 22

what do fruits develop from?

Answer 22

the ovary

Question 23

what are the the four adaptive advantages to angiosperm style fertilization?

Answer 23

1. food store for seed (endosperm) develops only after fertilization – double fertilization 2. Fruit development is usually triggered by fertilization 3. Female gametophyte is reduced in size and hence cheaper to produce 4. Production of the small female gametophyte takes few days rather than a few months – annual plants

Question 24

what are 6 differences between monocots and eudicots?

Answer 24

Question 25

what is the structure of the mature seed?

Answer 25

• embryo is inclosed by hard protective seed coat

Question 26

why does the seed undergo a state of dormancy?

Answer 26

• increases chances that germination will occur at a time and place most advantagous to seedling
• sometimes requires environmental cues to break dormancy

Question 27

what is a difference between monocots and eudicots?

Answer 27

• M: one cot + large endosperm
• E: 2 cots at embryonic axis

Question 28

what is a common type of asexual reproduction in angiosperms?

Answer 28

fragmentation

• separation of parent plant into parts that develop into whole plants

Question 29

what are the two kinds of flowers (ecious)

Answer 29

• monoecious: M and F flowers on same individual plant
• dioeciuos: M and F flowers on individual plants

Question 30

what are 3 mechanisms that prevent self-fertilization?

Answer 30

1. dioecous species
2. stamens and carpels mature at different times
3. self-incompatibility - rejects its own pollen triggering signal transduction pathway leading to a block in pollen tube growth