Unit 4: 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 

 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.  HfFvAZg HfFvAZg

 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.

 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.

 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.

 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.

 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.

 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.

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

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

 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

 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.

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

Structure:  Two tissue types: xylem and phloem  Xylem: thick-walled cells, dead at maturity  Phloem: thin-walled cells, living at maturity Function:  Transport water and nutrients  Support the plant body

Structure: Three tissue types:  Parenchyma: thin-walled cells, living at maturity  Collenchymas: thick-walled cells, living at maturity  Sclerenchyma: cells with lignin in their cell walls, dead at maturity

 Perform cellular processes to support growth and development (parenchyma and collenchyma)  Store carbohydrate, especially starch (parenchyma)  Support and protect plant body (collenchyma and sclerenchyma)

 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)

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

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 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.

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