Plants 2022

Plants

Plants

All plants have these characteristics in common:​

• Autotrophic: make their own glucose through photosynthesis.

• Multicelluar: more than one cell

• Eukaryotic: they have a nucleus and complex organelles

• Non-Motile: Unlike animals, they cannot move freely

• Sexual or asexual reproduction: some plants produce sperm and egg while others create clones

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Plant cells

In addition to the animal organelles, plant cells also have:​

Chloroplasts: site of photosynthesis

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Cell Wall: Provides a rigid structure over the cell membrane.

Made of cellulose.

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Central vacuole: Stores large amounts of water and provides turgor pressure.

​Plants - Levels of Organization

Plant only have 2 body systems:

Roots & Shoots

Roots: parts below ground

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Functions of root system:

1. Brings in water and nutrients from the soil

2. Anchors and stabilizes the plant

Shoots: Parts above ground

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1. Leaves: (photosynthesis)

2. Stems: (storage & transport)

3. Flowers / fruits / cones: (reproduction)

​Are plants vascular?

A nonvascular plant growing on a vascular plant

Plant Tissues - Plants may have vascular tissue, dermal tissue, and ground tissue.

1. Vascular Tissue: Transports water and nutrients throughout plant

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a. Xylem non-living; transports water

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b. Phloem living; transports nutrients

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Water Transport

Water is absorbed by the roots. 

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Roots contain hairs that increase the surface area, allowing for increased water absorption.

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Water Transport

Then, water travels up the plant through the vascular tissue called xylem.

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Xylem is a one-way street!

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Water moves from:

Root --> Stem --> Leaves

​How to remember xylem transports water??

THINK!   Water  and XYlem… like your abc’s! WXY(Z)

Water Transport

Most of the water does not go into a cell, but rather escapes out of the leaves through pores called STOMATA.

This process whereby water escapes is called:​

transpiration.

Nutrient Transport

The nutrients made by photosynthesis are transported by the vascular tissue called phloem!

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Phloem flows all around!

(unlike the one way street of xylem)

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Nutrient Transport

How to remember phloem transports nutrients?

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THINK!

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Nutrients = Food and Phloem… 

food and phloem both start with “F” sound!

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Plants & Reproduction

Non-flowering plants do asexual reproduction by spores.

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Flowering plants do sexual reproduction by sperm & egg.

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Stamen : male part

Includes:

Anther - produces pollen grains (sperm)

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Filament -  support structure for anther

Pistil (carpel): female part

Stigma - (sticky!) where pollen grains land.

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Style - tube that connects the stigma to the ovary. Pollen travels down this tube.

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Ovules - female gametes; fertilized by pollen.

Sepal: protects the flowers during development

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Petals: modified leaves that surround the reproductive parts.

Supporting Parts

Pollination

Flower petals are often large, brightly colored and fragrant.

This is to attract pollinators!

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Pollination: The transfer of pollen from the anther to the stigma.

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Common pollinators:

Hummingbirds, moths, bees, butterflies, bats, etc.

Pollination

Some plant have petals that are reduced or absent. These plants are pollinated by:

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Wind  ​

Water

Fertilization

Fertilization : The merging of the haploid sperm and egg to create a diploid embryo, which grows from a seed.

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Fertilization

​Over time, the ovary turns into a fruit.

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Fruit : a ripened ovary containing the seeds.

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Gas Exchange

Carbon dioxide (CO2) enters through the stomata.

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Stoma close when there is little water​ and the plant needs to prevent water loss through transpiration.

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Stoma also close at night when photosynthesis is not occuring.

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Gas Exchange

Plants have both mitochondria and chloroplasts, so they do both cellular respiration and photosynthesis.

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(This means they need both oxygen and carbon dioxide).​

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Why care about plants?

Lucky for us, plants generally go through photosynthesis much more than cellular respiration. This means plants produce an excess of oxygen and glucose!

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​They store the glucose as starch. We take it in when we eat!

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The oxygen exits the stomata and goes into the air for us to breathe!

Tropism

Tropism: directed growth in response to a stimulus.

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Tropisms are regulated by the hormone auxin.

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Tropisms can be positive (towards a stimulus) or negative (away from a stimulus).​

TYPES OF TROPISMS:

Phototropism = a plant's response to light.

TYPES OF TROPISMS:

Gravitropism (a.k.a. geotropism) = a plant's response to gravity.

TYPES OF TROPISMS:

Thigmotropism: A plant’s response to touch

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Examples: Vining plants, Venus fly trap, Touch me not (sensitive plant)

TYPES OF TROPISMS:

Hydrotropism = response to water (typically roots)

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Thermotropism = response to temperature

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Chemotropism = response to presence of certain substances

Multiple Choice

A potted plant is laid on its side. The roots grow downwards, towards the earth, while the shoots grow upwards, towards the sky.

What sort of tropism is this plant exhibiting?

• Hydrotropism

• Geotropism

• Chemotropism

• Autotrophism

Multiple Choice

What sort of tropism is the plant in the image displaying?

• Phototropism

• Geotropism

• Hydrotropism

• Autotrophism