Week 7 Mastering Assignment CHEM1252

_____ cells are the cells that regulate the opening and closing of stomata, thus playing a role in regulating transpiration. Companion Guard Tracheid Casparian strip Sieve-tube member

Guard

Some plants growing in arid climates have small leaves and thick waxy cuticles on the upper epidermis. This is an adaptation for _____. decreasing water loss from leaves increasing transpiration decreasing water breakdown in photosynthesis increasing water absorption

decreasing water loss from leaves

What is the xylem?

one of the two types of transport tissue in vascular plants, phloem being the other; basic function of xylem is to transport water from roots to shoots and leaves, but also transports some nutrients

In roots the _____ forces water and solutes to pass through the plasma membranes of _____ cells before entering the _____. Casparian strip ... endodermis ... phloem Casparian strip ... endodermis ... xylem xylem ... endodermis ... Casparian strip Casparian strip ... ectoderm ... xylem transpiration ... endodermis ... xylem

Casparian strip ... endodermis ... xylem

_____ bonds are responsible for the cohesion of water molecules. Peptide Nonpolar covalent Hydrogen Polar covalent Ionic

Hydrogen

Which of the following plant organs may act as a source for translocation of sugars inside a plant? Young growing leaves Mature leaves Developing flowers Any non-green tissue

Mature leaves

Which of these are symbiotic associations? apoplasts root hairs Casparian strips mycorrhizae symplast

Mycorrhizae

The channels indicated by the pointer, are _____. (The figure shows a structure of the root. The arrow indicates the channel between the cell from the outer layer of the root and the inner one.) gap junctions mycorrhizae tight junctions plasmodesmata desmosomes

Plasmodesmata

According to the pressure-flow hypothesis, what mechanism causes the movement of phloem sap from sources to sink tissues? Transpirational pull from the leaves Solute potential differences between source and sink Pressure potential differences between source and sink Root pressure

Pressure potential differences between source and sink

Imagine a plant without phloem. For sugars to move from one region of the plant to another, what must happen? The sugars would be actively transported from cell to cell. The sugars will passively move down a concentration gradient. The sugars must be loaded into tracheids and vessel elements instead. It would be impossible for sugars to move.

The sugars would be actively transported from cell to cell.

_____ provide(s) the major force for the movement of water and solutes from roots to leaves. Translocation Transpiration Root pressure Bulk flow Transfer cells

Transpiration

What is a Casparian strip?

a cellular feature found in the roots of all higher plants; ring-like, hydrophobic cell wall impregnations; occur in the endodermis, an inner cell layer that surrounds the central vascular strand of roots

What are mycorrhizae?

a fungus that grows in association with the roots of a plant in a symbiotic or mildly pathogenic relationship

What are plasmodesmata?

a narrow thread of cytoplasm that passes through the cell walls of adjacent plant cells and allows communication between them

What is phloem?

the living tissue that transports the soluble organic compounds made during photosynthesis (known as photosynthate), in particular the sugar sucrose, to all parts of the plant where needed; transport process is called translocation.

What is transpiration?

the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers