Plant Systems

Types of Plant Cells  3 Basic Types of Specialized Cells:  1. Epidermal Cells  2. Ground Cells  3. Vascular Cells

Plant Parts  Meristem (AKA Apical Meristem)= is a region where new plant cells are generated. This is where the growth occurs.

Roots  Roots= anchor the plant and help it absorb water and minerals. These also store food.  The Root Cap is an umbrella-like covering at the tip of a root.  Root Hairs increase the absorbent area of a root.  Parenchyma Cells= are large cells that are used to store nutrients.  Sclerenchyma Cells= are cells that stack end to end inside the plant to form a tube-like structure.  Xylem Cells= are vascular cells that transport water within the plant.

Roots

Stems  Stems provide support for the plant elevating its leaves, flowers, and fruit.  Woody Stems have cells called cork and phellem.  Cork Cells= provide protection and prevent water loss.  Cuticle= is a waxy layer that covers stems and leaves to protect against water loss.  All stems have vascular cells.  Vascular cells are sometimes scattered throughout the stem or arranged in a ring.

Stems

Leaves  Cuticle= waxy layer on the outside of leaves. The cuticle prevents water loss.  Trichomes= some plants have these specialized hairs located outside the cuticle.  Guard Cells= form openings called stoma that open and close to regulate gas exchange.  The guard Cells will open during wet periods and close during dry periods to prevent water loss.  Water loss through leaves is called TRANSPIRATION.  Photosynthesis takes place in the parenchyma cells of leaves. Then the vascular cells called phloem cells transport the food (glucose) from the leaves to other parts of the plant.

Leaves

Plant Systems  Vascular vs. Nonvascular  Vascular= plants that have specialized tissues used to transport substances. (Most plants are vascular)  Nonvascular= plants without specialized tissues used to transport substances. (Ex. Moss)

Plant Systems  Vascular plants have phloem and xylem tissues that transport substances.  Xylem= carries water from the roots up to the leaves.  Phloem= carries sugar (glucose) made in the leaves down to the stem and the roots.

Plant Systems

 Plants respond to their external environment.  Tropism= a plant’s growth in response to an environmental condition.  Positive tropism= is when plants grow toward something.  Negative Tropism= is when plants grow away from something. (Shade)  Phototropism= plant growth toward a light source. (Ex. Sun)  Auxins= are hormones that plants use to grow in the desirable direction.

Plant Systems

 Many vascular plants reproduce with flowers.  Flower= a reproductive organ that makes seeds and pollen.

Plant Systems  Male Structure of a flower:  Stamen  Anther= top part of the stamen that produces pollen

Plant Systems  Female Structure of a Flower: Pistil= made up of the ovary, style, and stigma. The seed is located inside the ovary. The Pollen Tube is inside the Style. Pollen travels down the pollen tube to fertilize the seed.

Plant Systems

 Self-pollination= occurs when the pollen of a flower is transferred to the stigma of the same flower.  Cross-pollination= occurs when the pollen from one flower is deposited on other flowers.

Plant Systems

Plants & Light

 ROY G BIV (Color Spectrum)  The light waves reflected are the color that you see. For example: A leaf reflects the light waves that are green in color ( nm)  Pigments= are substances that absorb light.  Chlorophyll a and b are the two main pigments of plant cells.

Plants & Light

 Plants have chromoplasts (plant pigments) that have light waves with higher frequencies. For example: A banana appears yellow or a flower appears blue.  Plants reserve these specialized colors for specialized parts, because higher frequencies mean they carry more energy.

Plants & Light

Photosynthesis  Photosynthesis is the chemical process plants use to trap energy from the sun and convert that energy, water, and carbon dioxide into sugar and oxygen.  Photosynthesis takes place inside the chloroplast, which is located in each plant cell.  The main result of photosynthesis is sugar molecules.  Photosynthesis has two basic stages:  1. Light-dependent Reactions  2. Light-Independent Reactions

Photosynthesis  Light-Dependent Reaction=  First, sunlight hits the leaf of the plant where it is absorbed by the pigments in the leaf. This forms ATP and NADPH (these are energy molecules)  Light-independent Reaction=  Then, the ATP and NADPH are used to form sugar molecules (glucose)

Photosynthesis  Photosynthesis can be slowed down or sped up, depending on environmental factors.  For example, very cold or very hot temperatures slow down photosynthesis.

Photosynthesis  The amount of reactants and light levels have a positive relationship with the rate of reaction. So the more reactants there are, the faster the reaction will happen.