Plants

By Gracie Lawrence, Kylie Carter, & Kaia Stefurak

Learning Objectives:

28.1 - Understand plant structure & organization

28.2 - Understand primary & secondary growth

30.1 - Learn how flowers, double fertilization, and fruits are

unique features of the angiosperm lifestyle

30.2 - Learn how flowers reproduce sexually, asexually, or

both

31.1 - Understand how plant hormones help coordinate

growth, development, and responses to stimuli

31.2 - Learn how responses to light are critical for plant

success

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1.Angiosperm

Structure

( 28.1 )

4

Root System:

Root - An organ that

anchors a vascular plant

in the soil, absorbs

minerals and water, and

stores carbohydrates.

5

Shoot System:

6

Stem - Orient shoot to

maximize

photosynthesis

Leaf - Main

photosynthesis organ.

Tissue Systems:

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Dermal - Plant’s protective

outer covering.

Vascular - Facilitates

transport of materials

through the plant, and

provides mechanical

support.

Ground - Includes storage,

support, and transport

cells.

2.

Angiosperm

Growth

( 28.2 )

Indeterminate

Growth

throughout a

plants life,

continuously.

Determinate

Growth that

stops once the

plant reaches a

certain size.

10

Primary Growth

Grows both above ground and below ground allowing

plant to get taller.

*SAM & RAM

11

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Secondary Growth

Increase of width in a plant by cell division in lateral

meristems

14

Vascular Cambium

Adds secondary xylem and phloem

Cork Cambium

Replaces with a thicker periderm

15

16

Reproduction cycles

and organs

Pollination and fertilization

● Flowering plants are angiosperms● Seed bearing plants are gymnosperms

● Fertilization in angiosperms requires gametophytes

● Male gametophyte is the pollen grain● Female gametophyte is the embryo sac

17

Pollen Formation

● Cells within a flower’s anther undergo meiosis to form four haploid cells

● Each cell divides by mitosis into a haploid male gametophyte consisting of two cells

● A thick wall forms around these cells

18

PP

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Pollination Methods

Pollination is the transfer of pollen to a plant’s female reproductive organs to allow for fertilization.

● Pollen is usually spread with the assistance of wind or wildlife, such as birds, insects, and mammals.

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Embryo sac formation

1. One cell in a plant’s ovule, which consists of many undeveloped cells, enlarges

2. This cell undergoes mitosis to form 4 haploid megaspores

3. One megaspore survives per ovule, the rest degenerate

This process takes place in many ovules in the plant’s ovary and results in an embryo sac ready for fertilization 21

Fertilization

● Fertilization in plants is the action or process of a pollen grain fertilizing an embryo sac to produce a zygote

● In flowering plants, two male calls are released and bind with two parts of the female organ in a process called double fertilization

Double fertilization occurs so the plant will not waste resources developing tissue for an ovule that has not been fertilized. 22

Fertilization process

1. After pollination, the pollen shoot grows towards the plants ovary

2. It punctures the plants ovule and discharges two male cells into the fully-formed embryo sac

3. One male cell fertilizes the egg, while the other fuses with the polar nuclei located in the center of the ovule.

This process results in a fertilized egg as well as a triploid which will develop into endosperm, the food storing tissue of a seed. 23

Fruit development

● After fertilization, each ovule develops into a seed and the ovary develops into a fruit

● For the most part, nutrients for the seed are stored in the endosperm

● Many different types of fruit develop bases on their developmental origins

24

Asexual reproduction

Asexual reproduction is usually an extension of a plant’s capacity for indeterminate growth

● One type of asexual reproduction is fragmentation, or the separation of an individual plant into parts which develop into full plants.

● Another type is apomixis, or asexual reproduction of seeds.

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5. Plant

Hormones and

Tropisms

( 31.1)

Auxin -

Stiumulates stem elongation and promotes

the growth of lateral roots.

Cytokinins -

Regulate cell division in shoots and roots and

stimulate growth of axillary buds.

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Gibberellins -

Produced in leaves and stems, and influence

fruit development and seed germination.

Abscisic Acid -

Slows plant growth and inhibits seed

germination (promotes dormancy).

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6. Responses to Light

(31.2)

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Tropisms

Plant’s directional movement due in response to

stimuli.

31

Geotropism

Plant’s directional response to gravity

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Thigmotropism

Plant’s directional response to a solid object

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Phototropism

Plant’s directional response to light