Plant Structures and Reproduction

1. Describe the Process of alternation of generations The life cycle of land plants has two alternating phases, a haploid (N)

phase and a diploid (2N) phase.o Gametophyte (N) : Gamete-producing planto Sporophyte (2N) : Spore-producing plant

This occurrence is called the alternation of generations. Different types of plants have different dominant stages:

o Bryophytes: Gametophyte (D) - comprises the main plant (eg. Green

moss or liverwort) Sporophyte - attached to gametophyte

o Tracheophytes (gymnosperm & angiosperm): Gametophyte – very small and cannot exist

independently Sporophyte (D) – the reproductive structures of the

(cones/flowers) produce microspores (m) and megaspores (f)

o Pteridophytes (seedless) Sporophyte is dominant

2. Describe the adaptation of bryophytes Lacking leaves, roots, and vascular tissues, the first land plants were

only a few centimeters tall. They grew close to the ground in damp locations so they can obtain water.

3. Explain the importance of vascular tissue Vascular tissue is the transport system in

plants, allowing passage of materials necessary for a plant to live

Vascular plants are called tracheophytes

o Tracheophytes have special cells called tracheids, which are tube-like cells with thick cell walls strengthened by lignin

Opening between tracheids known as pits allow water to move through a plant more efficiently than diffusion alone

2 types of vascular tissue :o Xylem – Transport water and nutrients from the roots to the

leaveso Phloem – Carries photosynthetic products/food from the

leaves to other parts of the plants

4. Describe the reproductive adaptations of seed plants Angiosperm

o Seeds covered with a protective seed coato Winged seeds, nuts, berrieso Bright flower colors to attract pollinators to trigger pollinationo Fruits disperse seeds by animals

Gymnospermo A large variety of gymnosperms have winged seeds, so they

can disperse their seeds using windo Others have nuts, which are dispersed by nut-eating animals

5. Explain the structures of mosses, ferns, conifers, and flowering plants Mosses

o Sporophyte Seta – supporting stalk Capsule – produces

sporeso Gametophyte

Stem – weak, short if free-standing

Rhizoids – hair-like, anchors plant and absorbs nutrients

Fernso Frond – The leaf of a fern, for

photosynthesis and reproductive functions

o Rhizome – The stem of the fern plant, produces roots and fronds

o Sporangium – Capsule that contains spores

o Sorus – Cluster of sporangia

Coniferso Cones

Pollen Cones – Male cones, produces pollen grains, makes up the entire male gametophyte

Seed Cones – Female cones, produce female gametophytes, larger than pollen cones

Flowering Plantso Stamen (Male)

Anther – structures in which pollen grains are produced

Filamento Carpel (Female)

Stigma – Sticky or feathery, captures pollen

Ovary – Encloses ovum which will become the seed, develops into fruit

6. Explain the life cycles of mosses, ferns, conifers, and flowering plants

Mosses

Ferns

Conifers

Flowering Plants

7. Identify some of the ways angiosperms can be categorized Monocot

o Single cotyledono Parallel veins in leaveso Floral parts in multiples of 3o Scattered vascular bundleso Fibrous roots

Dicotso Two cotyledonso Branched veins in leaveso Floral parts in multiples of 4 and 5o Vascular bundles arranged in a ringo Taproot

8. Differentiate between complete or incomplete and perfect or imperfect flowers Complete flowers contain:

o Sepalo Petalo Stamen (Male)

Anther Filament

o Carpel (Female) Stigma Style Ovary

Incomplete flowers lack any one or more of these parts Perfect flowers contain both male and female parts in the same plant Imperfect flowers only contain either male or female parts All Complete flowers are perfect flowers, but not all perfect flowers

are complete flowers

9. Identify the functions of various structures in a flower Sepal – Protects flowers while it is developing Petal – Brightly colored, attracts pollinators to the flower

Pollen – Yellowish dust that contains male gametophytes Stamen (Male)

o Filament – Stalk holding up the anthero Anther – structures in which pollen grains (male

gametophytes) are produced Carpel (Female)

o Stigma – Sticky or feathery, captures polleno Style – The stalk of the carpelo Ovary – Encloses ovum, will become fruit to disperse seeds

10. Explain how fertilization differs between angiosperms and other plants Angiosperms have a fertilization process called double fertilization, in

which two sperm cells are involved :o The first sperm fertilizes the egg cell forming the zygoteo The second sperm fuses with the two polar nuclei forming the

endosperm (3N) Here are the steps of double-fertilization :

o After pollen is deposited on the stigma it germinates and grows to the style to reach the ovule:

The microspores (or pollen) contain the pollen tube cell and the generative cell

The pollen tube cell digs a tube through the style for the generative cell to travel in

The generative cell divides into two sperm cells, which enter the ovule sac through the micropyle

One sperm fertilizes the egg cell forming a zygote (2N) The other sperm fuses with the two polar nuclei, forming

the endosperm (3N) The fertilized ovule forms the seed No other sperm can enter after the fertilization is

complete

11. Describe the effects of hormones on plant growth and development Hormones are chemical signals produced by living organisms that

affect growth, activity, and development of tissues and cells Coordinates responses to environment How hormones act

o Target cell – cell in an organism affected by the hormoneo Receptor – Protein to which hormone molecules bindo Cells that don’t contain receptors are unaffected by hormones

5 general classes of hormoneso Auxins

Stimulate cell elongation and the growth of new roots Regulate cell division in meristem Inhibit lateral buds Produced in the shoot apical meristem and transported

to the rest of the plant Apical Dominance

The phenomenon whereby the main central stem of the plant is dominant (grows stronger) over the other side of the stems

o Cytokinins Stimulate cell division in shoots Interact with auxins to help to balance root and shoot

growth Stimulate regeneration Delay aging of leaves Produced in growing roots and in developing fruits and

seeds Can Inhibit the growth of new roots (opposite effects to

those of auxins)o Gibberellins

Stimulate growth and causes dramatic increase in size in stems and fruits

o Absisic Acid Control seed dormancy

Inhibit cell division Promotes seed dormancy

o Ethylene Gaseous form Stimulate ripening of fruits Cause plants to seal and drop off unnecessary organs

12. Identify the three tropisms exhibited in plants Tropism is a plants growth response to environmental stimuli Types of tropism :

o Phototropism Plants’ response to light eg. Plants’ growing towards the light

o Gravitropism Plants’ response to gravity eg. Plants’ root going down

o Thigmotropism Plants’ response to touch eg. Vines growing on walls

Negative tropism – When the plant grows away from the stimulio eg. Plant stem grows upwards (negative gravitropism)

13. Describe how plants respond to seasonal change Photoperiodism – Responses of plants to the relative lengths of the

light and dark periods Phytochrome – Plant pigments that respond to photoperiodism Types of plants

o Short day plant – Needs an extended period of darknesso Long day plant – Needs an extended period of brightness

Dormancyo When an organism’s growth and activity stops or decreaseso These occurrences may happen :

Leaf loss Changes to the meristem Thick, waxy scales form a protective layer around the

new leaf buds

Additional Information

Plant classification

Double fertilization

Plants

Vascular

Seed

Gymnosperm

Angiosperm

Seedless

Pteridophytes

Non- Vascular

Bryophytes

Micropyle

Antipodal

Polar Body

OvumTube cell digs a tube through the style

Generative cell divides into two sperm cells

Style

Ovary