SBI3U1. Plants can reproduce both sexually and asexually.
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Transcript of SBI3U1. Plants can reproduce both sexually and asexually.
PLANTS: REPRODUCTION, GROWTH & SUSTAINABILTY
SBI3U1
PLANT REPRODUCTION
Plants can reproduce both sexually and asexually
Sexual reproduction is by sporic reproduction (alternation of generations).
Haploid gametophyte cells (1n) produce gametes
Diploid sporophyte cells (2n) produce spores.
Male and female gametes unite to form the sporophyte that continues the life cycle.
Sexual Vs. Asexual Reproduction
Plant Reproduction
Sexual
Seedless Plants
Non-vascular Vascular
Seed Plants
Gymnosperms Angiosperms
Asexual
Natural Vegetative
PropagationArtificial
Propagation
OVERVIEW
Copy chart on pg. 583 (textbook)
Sexual Reproduction in Seedless Plants
-Fertilization -> the sperm swims from the male gametophyte to the egg in the female gametophyte.
-Water must be present & sperm must have a flagellum.
Ex. gymnosperms and angiosperms Male gametophytes called a microspore,
develop into a pollen grain and sperm. Female gametophyte, called a macrospore,
develops into an egg cell. In order for pollination to occur; male gametophyte must be transferred to the female reproductive structure.
Sexual Reproduction in Seed Plants
Angiosperms
sepals – protect the flower budpetals – attract pollinators
4 Basic Flower Organs
stamens – male reproductive structurepistils – female reproductive structure
• The reproductive structures are in the flowers.
• Fertilization & seed development occur within the ovule.
• Pollination takes place on the stigma.
• Female gametophytes develop in the ovules, where eggs are formed.
Variations Among Flowers◦ Complete flowers – Contain all four flower organs◦ Incomplete – Missing one or more flower organs
Grass flowers lack sepals and petals. They are incomplete.
Self-pollination: Plants pollinate themselves Cross-pollination: Plants receive pollen from another plant.
Animal Pollination: Insects and other small animals move from flower to flower collecting nectar and moving pollen. Bright, sweet-smelling flowers attract these pollinators.
Wind Pollination: Wind carries pollen and it lands on a receptive reproductive organ.
4 Pollinating Mechanisms
Self Pollination vs. Cross Pollination
Label your diagram using handout
Seed & Fruit DevelopmentFertilization is one long process that ends with the formation of a seed.A seed is part of a fruit, developed from the ovary
Monocot vs. Dicot SeedsThe outside layers of the ovule form a protective cover called the seed coat. Ex:Beans or peas have seed coats that can easily be peeled off
Seed germination A Seed may remain dormant for a period of time and then resumes growth
Produces genetically-identical clones from a parent
Vegetative propagation – Involves growing a new individual from only a portion of the original plant
Asexual reproduction
8 Types of Vegetative Propagation
1.Division Splitting 2.Grafting
8 Types of Vegetative Propagation
3. Leaf Cutting 4. Stem Cutting
8 Types of Vegetative Propagation
5. Root Cutting 6 Simple Layering
8 Types of Vegetative Propagation
7. Air Layering 8. Cell Culturing
PLANT GROWTH & DEVELOPMENT
Plant HormonesHormone: chemical compound produced in one part of the plant that controls growth in another part of that plant
act as chemical signals between cells and tissues
Some stimulate growth, others inhibit growth
1. Auxins2. Cytokinins3. Gibberellins4. Ethylene5. Abscisic acid
5 Main Plant Hormones:
“to increase” stimulates elongation of plant cells Produced in developing leaves/seeds and
shoot tips Controls upward growth – apical
dominance
Stimulatory Hormones:1.Auxins
Promotes cell division & differentiation Stimulates the production of proteins
required for mitosis and cytokinesis delays aging of leaves and fruit
Stimulatory Hormones:2. Cytokinis
Stimulates taller, stronger plant growth Stops dormancy in seeds Used in commercial crops to increase fruit
size or larger cluster size in grapes
Stimulatory Hormones:3. Gibberellins
Promotes ripening of fruit Gaseous hormone Diffuses through spaces in cells and
transported within phloem
Inhibitory Hormones:4. Ethylene
Induces seed dormancy Inhibits growth of buds in plant stems Closes stomata & blocks intake of CO2
Inhibitory Hormones:5. Abscisic Acid
Nastic response: a movement of the plant that is reversible, repeatable, and does not include growth. Ex: the opening & closing of flower petals as light conditions change.
Plant Responses to Environmental StimuliUNIT 5 Chapter 14: Plants: Reproduction, Growth, and Sustainability Section 14.2
Tropic Responses
3 main Types:
Growth responses to external stimulation coming from one direction in the environment.
1)Phototropism2)Gravitropism3)Thigmotropism
a growth response to light produced by an unequal distribution of auxin.
More auxin on the side with less light causes those cells to elongate and bend the plant toward the light
1) Phototropism
Growth response to gravity a “positive” growth response of the roots downward or
a “negative” growth response of stems upward
2) Gravitropism
a growth response to mechanical stimuliContact with another object Ie. Ivy growing on a fence or tree
3) Thigmotropism
Other Factors that Affect Plant Growth
Nutrients Soil pH
Nutrients needed in large amounts are called macronutrients (ie.N, K, Ca, Mg)
Nutrients needed in small amounts are called micronutrients
( ie. Cl, Fe, B, Zn)
Optimal soil pH is slightly acidic ( pH 6-7) or slightly basic ( pH 7-8)
Any extremes in pH will inhibit normal plant growth