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