Plant Cells, Tissues, and Systems Sec C3.1 Unit C

Objectives describe the specialized structures and functions of cells in the leaf system explain the transport system in plants relate a multi-cellular level of organization with cell, tissue, and system specialization

Multicellular vs Unicellular What are the advantages to having a large structure with lots of cells? Division of Labour When a cell is specialized (performs a particular function), it is more effective and efficient. A single-celled organism must multi-task (do many jobs).

Multicellular vs Unicellular Size The surface area to volume ratio and related rate of diffusion restricts growth in unicellular organisms. Efficient transport systems within multicellular organisms allow for growth.

Multicellular vs Unicellular Interdependence of Cells A single-celled organism is dependent on that one cell. If a multicellular organism loses a cell, the entire organism will not die. However, a cell not functioning properly (ex. cancerous) can cause problems for the rest of the organism.

Plant Structure Plants are multicellular: made of many parts, each with its own function – organized in increasing complex levels of organization Tissues= group of cells performing same function together Organs= tissues contributing to same function System= group of interconnected organs (two in plants) Shoot system  everything above ground Root system  everything below ground and aerial roots

What about animals? What are some examples of tissues, organs and systems in humans? Ex. Heart/cardiac tissue  heart  circulatory system

Do now Find the definition/function associated with each of the following terms (workbook - chart) Meristem Dermal tissue/epidermis Cuticle Ground tissue Vascular tissue Xylem tissue Phloem tissue Sieve tube cells Companion cells

How did you do? Meristem- growth areas Dermal tissue/epidermis- outer layer of cells; responsible for exchange of matter and gases and protection Cuticle- waxy substance; resists attack and prevents water loss Ground tissue- majority of plant; strength and support (stem); food and water storage (roots); site of photosynthesis (leaves)

How did you do? Vascular tissue- transport of materials; xylem and phloem Xylem- moves water and minerals from roots to leaves; thick, non-living, perforated cells Phloem- transports sucrose and other sugars from leaves to other parts; made of sieve cells Sieve tube cells- form continuous ducts; perforated Companion cells- direct activity of sieve tube cells

Plant Growth Cells divide to grow and repair damage. This cell division is called mitosis. In plants, increase in size results from the cell division in growth areas called meristems Rapidly dividing cells - Cell walls thin, nuclei are large, vacuoles, small or absent

Meristems Onion root tip – note different stages of mitosis (cell division)

Specialization of Cells Once cells are no longer in the meristem, they will specialize Produce products only for their function The root and shoot systems are made up of 3 types of tissues: Dermal Tissue (epidermis) Ground Tissue Vascular Tissue

Types of Tissue Dermal Tissue Outer layer of cells that covers all herbaceous (non-woody) plants. Responsible for exchange of matter and gases into and out of the plant. Also protects the plant from disease. This is done by the cuticle (waxy substance), which resists attacks from micro-organisms and helps reduce water loss.

Types of Tissue Ground Tissue Found underneath epidermis, it makes up majority of plant. Provides strength and support to the plant (stem). Involved in food and water storage (roots). Location of photosynthesis (leaves).

Types of Tissue Vascular Tissue Responsible for transport of material, which occurs in xylem tissue and phloem tissue

Vascular Tissue - xylem Cells in xylem tissue allow transport of water Die when differentiate leaving empty tubes Long fibres in celery are vascular tissue (both xylem and phloem)

Vascular Tissue - phloem Phloem Tissue Formed from long sieve tube cells (no nuclei), which are connected with companion cells (nucleated) that direct activity. Transports carbohydrates and water from the leaves to other parts of the plant.

Leaf Cross section http://dendro.cnre.vt.edu/forestbiology/photosynthesis.swf

Vascular Tissue

Vascular tissue From: http://www.youtube.com/watch?v=4V0VcNCRKTo&feature=related at 4:14

Vascular Bundles

Sieve tubes

More specialization: Roots Cells in root system will produce tiny hair-like projections called root hairs Why is this beneficial for the plant? Increases the surface area for absorption of water

Root hairs

Root hairs

More … Dermal cells in shoot system produce a cuticle Why is this beneficial? Prevents water loss

And last… Lower epidermis in leaves have guard cells Form tiny pores called stomata for gas exchange Only cells with chloroplasts Why is this important? Photosynthesis!

Leaf Cross section http://dendro.cnre.vt.edu/forestbiology/photosynthesis.swf

Leaf Cross section Can you indentify some of the structures?

How does water move up the plant? Gravity should pull water down – how does it move up from the roots to the leaves? How do all these specializations allow for this? Shall be investigating this in this section. http://www.youtube.com/watch?v=U4rzLhz4HHk&fea ture=related