5. Chapter 30: Seed Plants

Question 1

What are the three main adaptations of angiosperms?

Answer 1

1. the advent of the seed 2. reduction of the gametophyte 3. evolution of pollen

Question 2

Define seed plants

Answer 2

vascular plants that produce seeds, an embryo packaged along with a store of food within a resistant coat

Question 3

FYI: Seeds as food

Answer 3

1. monoculture - a few seed crops dominate 2. single most important change 3. cultivation 10,000 years ago

Question 4

List three ways in which the gametophytes of seed plants differ from ferns and bryophytes.

Answer 4

1. microscopic 2. protected within the parental sporophyte 3. obtain nutrients from the parental sporophyte

Question 5

Where is the gametophyte in pine tree? in other angiosperms?

Answer 5

• In the cone (female and male pollen cones; mainly diploid but tiny gametophyte inside) - In angiosperms (in ovaries which is in the flower)

Question 6

What is the possible hypothesis for the adaptation to a dominant diploid sporophyte?

Answer 6

For harsh terrestrial environments, extra set of spare alleles in case one is damaged.

Question 7

Why would the gametophyte continue to persist?

Answer 7

functions as a form of genetic screening - no alleles can hide in a haploid organism (all have to be working)

Question 8

What does a seed consist of? What is the ploidy?

Answer 8

1. sporophyte embryo (2N) 2. food supply (N) in angiosperm (3N) 3. protective coat (2N) (improved solution to resist harsh environments; move through space and time)

Question 9

All seed plants are heterosporous. What does that mean?

Answer 9

produce two different types of sporangia and two types of spores (megaspores and microspores)

Question 10

What does the megasporangia produce?

Answer 10

via meiosis produce megaspores (N) to form multicellular female (egg-containing) gametophytes (N)

Question 11

What does the microsporangia produce?

Answer 11

via meiosis microspores (N) to form male (sperm-containing) gametophytes (N)

Question 12

What does the ovule consist of? What is its ploidy?

Answer 12

Diploid (2N): consist of integuments. megaspore, and megasporangium

Question 13

What does the zygote (egg fertilized by sperm) develop into? What does the ovule develop into?

Answer 13

sporophyte embryo; seed

Question 14

What’s integuments?

Answer 14

derives a seed’s protective coat

Question 15

Why is pollen an adaptation?

Answer 15

1. eliminated water for fertilization (lack flagella) 2. covered with tough coat containing sporopollenin 3. carried by wind or animals (developed from microspore contained within microsporangium)

Question 16

What are the most familiar phyla of gymnosperms? Other 3?

Answer 16

Conifers, the cone-bearing plants Ginko (single species: Gingko biloba), cycads, gnetophytes

Question 17

How did the Earth change during the formation of the supercontinent Pangaea (Permian)?

Answer 17

1. drier and warmer continental interiors 2. amphibians decreased in diversity, reptiles increased 3. horsetail ferns replaced by gymnosperms (suited to drier climate) 4. end of Permian (245 may) as boundary b/w Paleozoic and Mesozoic eras (mass extinction)

Question 18

List some distinct characteristics of phylum coniferophyta. Examples?

Answer 18

1. pollen. ovulues, seeds, born on cones, most evergreen, needle-shaped leaves, thick cuticle, stomata in pits, dominate Northern Hemisphere 2. pines, cedars, spruces, firs, etc. (BC: douglas fir, western red cedar, western hemlock) - largest and oldest organisms of Earth (heights of over 100m and 4,800 years old)

Question 19

Commercial uses of wood (dead xylem tissue)?

Answer 19

lumber and paper BC Forestry Industry dominates - $16 billion/year - 46% provincial exports - 8% global forest products

Question 20

8 steps reproduction in pine trees.

Answer 20

1. produce pollen cones and ovulate cones 2. microsporangia (va meiosis) to microspores (N) to form pollen grains (male gametophytes) 3. many scales in ovulate cone, each with two ovules; megasporangium via meiosis to form megaspores (N) to female gametophyte to egg 4. Pollination via wind to ovulate cone 5. Pollen grain digest through megaspore ( can take >1 year) 6. Megaspore via meiosis produce 4 haploid cells, one will develop to megaspore 7. megaspore to female gametophyte containing two or three archegonia (ea. with egg) 8. eggs ready, two sperms developed in pollen tube => fertilization (only 1 embryo develops)

Question 21

What does the pine seed consists of?

Answer 21

1. embryo (new sporophyte) 2. food supply (from gametophyte tissue) 3. seed coat (from integument of parent)

Question 22

Draw the gymnosperm life cycle.

Answer 22

Question 23

What are angiosperms? What two clades are they divided into?

Answer 23

• vascular seed plants that produce flowers and fruits (most diverse). - Monocots (monophyletic) and the eudicots (includes original dicots; not monophyletic)

Question 24

What is the defining reproductive adaptation for all angiosperms?

Answer 24

Flower, rely on insects and other animals to transfer pollen; some rely on random mechanism of wind pollination

Question 25

What is a flower? Draw it.

Answer 25

a specialized shoot with four circles of modified leaves: sepals, petals, stamens and carpels. (“perfect” flower has both female and male reproductive organs)

Question 26

What are the sepals?

Answer 26

base of the flower, modified leaves that enclose flower before it opens.

Question 27

What are petals?

Answer 27

lie inside ring of sepals and often brightly coloured to attract animal pollinators

Question 28

Are the sepals or petals involved in reproduction?

Answer 28

Not directly

Question 29

What are stamens?

Answer 29

male reproductive organs; produce microspores that will give rise to gametophyte. (pollen) consist of filament and anther (where pollen is produced)

Question 30

What are carpels?

Answer 30

female reproductive organs; produce megaspores that gives rise to female gametophyte (aka embryo sac)6 - sticky stigma receives pollen - style leads to ovary at the base of carpal - ovules and seeds protected within ovary

Question 31

What is a fruit?

Answer 31

a mature ovary; various modifications help disperse seeds

Question 32

6 Steps to angiosperms life cycle.

Answer 32

1. anthers produce microspores that form male gametophyte (pollen) 2. ovules produce megaspores that form female gametophyte (embryo sac) 3. pollen carried to sticky stigma of carpal 4.when pollen tube reaches ovule two sperm discharge into female gametophyte 5. double fertilization - one sperm unites with egg to form zygote (2N), other fuses with two nuclei in centre cell of female gametophyte 6. zygote into sporophyte embryo packages with food reserve (3N) and surrounded by seed coat. (Embryo has one or two seed leaves - aka the cotyledons)

Question 33

Draw the angiosperm life cycle.

Answer 33

Question 34

What is the hypothesis for the function of double fertilization?

Answer 34

• synchronizes development of food storage in seed with development of embryo to prevent squandering nutrients on infertile ovules (sperm and eggs mature at different times to ensure cross pollination although some self pollinate)

Question 35

What does the seed of an angiosperm consist of? What are the ploidy?

Answer 35

1. Embryo (2N) 2. Endosperm (3N) 3. Seed coat (2N) from integuments (Ovary develops into fruit) (Seed germinates if environmental conditions are favourable)

Question 36

What is coevolution?

Answer 36

mutual evolutionary influence between two species (i.e. insects responsible for plant diversity)

Question 37

How do humans influence earth’s flora?

Answer 37

1. Artificial selection: manipulate and select plants to maximize harvest (nearly all our food, grains aka grass fruits) - not the same as GMO (genetically modified organisms) 2. extinguishing plant species; extinction (plant diversity is nonrenewable resource

Question 38

Why do humans depend on fruits?

Answer 38

depend for food production and oxygen release, building materials, medicines