Lesson 1: Characteristics and Needs of Plants

Unit 4: Plants

What are the basic needs of plants?

1. Energy: Plants capture energy from incoming solar

radiation and convert it to chemical energy through photosynthesis, a complex process that uses carbon dioxide and water to form glucose and oxygen. The word equation for photosynthesis is:

solar energy

Carbon dioxide + water glucose + oxygen

 

Energy

Energy

Plants produce glucose which is a carbohydrate.

Chemical energy plants need for maintenance, growth, and development.

Photosynthesis needs: CO2 + H2O+light

Plants have many adaptations to gain light For example, some plants can adjust the position of their leaves to maximize their exposure to sunlight.

https://www.youtube.com/watch?v=EvX-HfFvAZg

Basic Needs of Plants:

2. Protection against herbivores: Plants get eaten.

Good for us/animals = bad for plants

Since plants cannot move theydeveloped other ways to protect themselves.

Ex: Many plants produce toxic or bad-tasting substances to keep herbivore away. Others produce a tough, hair, or prickly outer layer.

Protection

Basic Needs

3. Nutrients: Plants need nitrogen (N),

phosphorous (P), and potassium (K), in order to synthesis the proteins, lipids, and other compounds needed in their cells.

Plants absorb nutrients as dissolved substances in water.

Nutrients

Most plants are helped in this process by mycorrhizal fungi associated in their roots.

This fungi has a mutualistic relationship with the plant, whereby the plant provides the fungi with carbohydrates and in return, the fungi provides the plant with the nutrients by its ability to absorb water and minerals.

Basic Needs

4. Water: Plants need water for photosynthesis

and many other processes, such as growth and repair of cells.

If a plant loses too much water it will wilt and may die; similarly, it may die if it is exposed to too much water.

Basic Needs

5. Gas Exchange: Plants are living organisms and need

to exchange gases with the environment during processes such as photosynthesis and cellular respiration.

In vascular plants, most gas exchange happens in the leaves.

Basic Needs

6. Reproduction: Plants need to reproduce.

asexual and sexual reproduction – meaning that male and female gametes, usually from two individuals, have to meet and join.

Since individual plants cannot move, plants have evolved some amazing adaptations to ensure that their gametes unite and that the resulting zygote has an appropriate environment in which to germinate and grow.

Roots & Shoots Flowering plants are divided into two main'body systems' – roots & shoots

Root System

The Root System: Includes all the root material Underground (usually) Anchor the plant in the soil Absorb water and nutrients Conduct water and nutrients Food storage

Shoot System

The Shoot System: Includes the stems and leaves (and

reproductive parts) Above ground (usually) Elevates the plant above the soil Many functions including:

Photosynthesis Reproduction and dispersal Food and water conduction

3 Basic Tissue Types in Plants

Vascular plants have three main non-reproductive organs: the leaf, the stem and the root. These organs are primarily composed of three tissue types: dermal tissue vascular tissue ground tissue.

Dermal Tissue

STRUCTURE: Two tissue types: epidermis and

periderm Outermost cell layers Often have thicker cell walls Covered with a waxy cuticle

FUNCTION: Protect against injury, herbivores,

disease and water loss

Dermal Tissue

Vascular Tissue

Structure: Two tissue types: xylem and phloemXylem: thick-walled cells, dead at

maturityPhloem: thin-walled cells, living at

maturity

Function: Transport water and nutrients Support the plant body

Vascular Tissue

Ground Tissue

Structure:Three tissue types:Parenchyma: thin-walled cells,

living at maturityCollenchymas: thick-walled cells,

living at maturitySclerenchyma: cells with lignin in

their cell walls, dead at maturity

Ground Tissue

Perform cellular processes to support growth and development (parenchyma and collenchyma)

Store carbohydrate, especially starch (parenchyma)

Support and protect plant body (collenchyma and sclerenchyma)

Ground Tissue

Meristematic (Meristem) Tissue Area of actively dividing undifferentiated

cells.

Eventually develop into specialized cells and tissues.

Produce new cells through mitosis.

In plants, mature cells cannot divide. This means that the plant can only grow where there is meristematic tissue. (root tips, buds)

https://www.youtube.com/watch?v=h9oDTMXM7M8

Phylogeny

There are three major groups of vascular plants Lycophytes and pteridophytes Gymnosperms Angiosperms

Lycophytes and Pteridophytes

Gymnosperms

Angiosperms

Phylogeny

https://www.youtube.com/watch?v=gTQ9gsZBMPI

Phylogeny

Monocots & Dicots

Angiosperms have traditionally been divided into monocots or dicots based on whether the seeds of angiosperms have one or two cotyledons.

Cotyledons are a structure in the seeds of flowering plants (angiosperm) that stores and supplies nutrients to the embryo.

Cotyledons

Monocots & Dicots

Monocots & Dicots

Monocot & Dicot

Monocots & Dicots

https://www.youtube.com/watch?v=gI2RxzAT-ww