MUIDS G11 Advanced Biology Plantae

General characteristics of plants

General characteristics of plants

• Multicellular

• Autotrophic

• Cell wall made of cellulose

• Store carbohydrates as starch

• Cellular respiration

Autotrophic

Can produce their own food and energy through the process of photosynthesis

Classification of plants

1. Bryophytes

2. Tracheophytes

Bryophytes

Nonvascular plants

Tracheophytes

vascular plants

2 types of tracheophytes

gymnosperms and angiosperms

Gymnosperms

Cone-bearing plants

Angiosperms

flowering plants

2 types of angiosperms

monocots (one embryonic leaf) dicots (multiple embryonic leaf)

Taxonomy

Chloroplast -> anchoring roots -> vascular tissue -> seeds -> flowers

Problems faced by plants before evolution

(imagine a seaweed)

• no body support

• not able to absorb and conserve water

solutions to problems

Structure, support and protection

• cell wall

• gametangia

• sporopollenin

Absorb and conserve water

• roots

• stomata

• cutin (waxy covering)

• seed coat

gametangia

A reproductive organ that houses and protects the gametes of a plant

sporopollenin

pollen or spore cell wall

plant growth

primary growth and secondary growth

Primary growth

• Vertical growth

• Growth by apical meristems, which lengthen stems and roots.

Secondary growth

• Lateral growth

• Growth by lateral meristems and/or intercalary meristems, which increases the girth of the plant

Types of roots

• taproot: single, large, deep root

• fibrous root: multiple, small and net-like

• adventitious roots: roots above ground

• Aerial roots: branching in air

• Prop roots: grow out from the base of the stem

Function of roots

• absorb nutrients

• anchor plants

• store food

structure of roots

• Epidermis

• Cortex

• Stele

• Endodermis

Epidermis

• outer layer of skin

• absorption

• composed of root hair (increases surface area for better rate of absorption)

Cortex

ground tissues:

• parenchyma

• collenchyma

• sclerenchyma

Stele

vascular cylinder (inside endodermis):

• xylem

• phloem

• pericycle

Endoderm

layer surroudning the vascular cylinder

Casparian strip

ring of waxy material made of suberin lipid that prevents apoplast

Absorption

The transport of dissolved substances into cells.

types of lateral movement

symplast and apoplast

symplast

System of transport within a plant cytoplasm consisting of openings in cell walls called plasmodesmata

• continuous system

• osmosis

Plasmodesmata

Openings in cell walls of plants for the passage of materials from one cell to another.

apoplast

System of transport through intercellular space and cell wall

• not a continuous system

• use pressure for transportation

symbiotic relationship

close interaction between species in which one species lives in or on the other

mycorrhizal fungi

fungi that surround plant roots and help plants obtain water and minerals

Rizhobium bacteria

nitrogen fixing bacteria in leguminous plants

stem

supporting structure that connects roots and leaves and carries water and nutrients between them (function: support and transport)

vascular bundels

xylem and phloem

ground tissue

cortex and pith

Leaf

the main organ of photosynthesis and transpiration in plants

Structure: Epidermis - protection Cuticle - prevent water loss Guard cells - control stomata opening Palisade mesophyll - photosynthesis Spongy mesophyll - photosynthesis Veins - Carry water and nutrients

stomata

Small openings on the underside of a leaf through which oxygen and carbon dioxide can move

For transpiration and gas exchange

4 types of plant tissue

dermal, vascular, meristematic, ground

Parenchyma

Fundamental tissue composed of thin-walled living cells that function in photosynthesis and storage.

Collenchyma

type of ground tissue cell with a strong, flexible cell wall; helps support larger plants

Sclerenchyma

type of ground-tissue cell with an extremely thick, lignified cell wall that makes ground tissue tough and strong

Xylem

vascular tissue that carries water and minerals

• transport only in upward direction

• made of two types of cells: tracheid and vessel element

• method: diffusion + transpirational pull + cohesion tension

Phloem

Living vascular tissue that carries sugar and organic substances throughout a plant

• two-way flow

• made of two types of cells: sieve tubes and companion cells

• method: osmosis + translocation / pressure flow

Plant reproductive structures

pistil and stamen

Pistil

The female reproductive part of a flower

Stigma - capture pollen Style - tube that leads pollen down to ovary Ovary - contains ovules and embryo sacks

Stamen

the male reproductive organ of a flower

Anther - pollen Filament - tube attached to the anther

Sepal

outermost leaf of the flower

petal

A colorful, leaflike structure of some flowers that attracts pollinators

asexual reproduction in plants

• Grafting

• Cutting

• Bulbs

• Runners

sexual reproduction in plants

pollination and fertilization

pollination

Pollen(2 haploid nuclei: 1 tube and 2 sperms) + egg

• Pollen grain germinates → forms pollen tube

• Fertilize egg → embryo

• Fertilize polar bodies → cotyledon

seed

The plant structure that contains a young plant inside a protective covering

structure of plant seed

• seed coat

• embryo

• cotyledon / endosperm

3 parts of plant embryo

1. Hypocotyl (root and stem)

2. Epicotyl (shoot / upper stem)

3. Radicle (embryonic / baby roots)

alternation of generations

A life cycle in which there is both haploid(gametophyte) and diploid(sporophyte) form

Alternation of generation in bryophytes (mosses)

Gametophyte dominant

Alternation of generation in fern and seed bearing plants

Sporophyte dominant

types of seed bearing plants

gymnosperm and angiosperm

Tropism

A growth response of a plant toward(positive) or away(negative) from a stimulus

Thigmotropism

A growth response to touch

Geotropism/Gravitropism

response of a plant to the force of gravity

Phototropism

A growth response to light

Hydrotropism

a plants growth response to water

tropism is caused by hormones

1. Auxin (promote growth and elongation)

2. Cytokinins (promote cytokinesis -> cell division)

3. Gibberellins (stem and leaf elongation)

4. Abscisic acid (inhibits growth)

5. Ethylene (ripening of fruits)