BIO242: Exam 2

Describe two different functions of roots.

• Absorption of water & minerals

• Anchors plant into soil

What embryonic structure develops into the first root?

Radicle

Fibrous Root System

Large number of smaller roots

Taproot System

Large central root

Food Storage Roots

Stores starches & carbohydrates

Water Storage Roots

Store water

Pneumatophores

Grow underwater

Parasitic Roots

Have no chlorophyll and take chlorophyll from other plants nearby

What are root nodules and how do they benefit plants? Explain the benefits of crop rotation.

Root nodules are clusters of cells containing nitrogen-fixing bacteria (rhizobia). They benefit plants by fixing nitrogen and utilizing elements.

Crop rotation is beneficial because single crops deplete nutrients in the soil so rotating and using multiple crops allows each crop to use the nutrients from the last crop. Crop rotation also helps the plants to become more resistant to diseases.

Parts of a woody stem from TOP to BOTTOM (A-F)

Terminal Bud, Axillary Bud, Bundle Scar, Terminal Bud Scale Scar, Lenticel, Leaf Scar (TABTLL)

Wood

Secondary Xylem

What is an annual ring and how can they be used to study climate history?

An annual ring is the amount of xylem that forms over a year. They tell us the age of the tree and the size/color characteristics of the annual ring can tell us the climate the tree experienced during that year.

Tuber Stem

Underground potato stem used to store starch

Runner Stem

Horizontal, above-ground strawberry stem used for asexual reproduction

Bulb

Underground onion bud surrounded by fleshy leaves attached to a small stem

Tendrils

Slender pea stems that coils around other objects and helps the plant to climb.

Cladophyll

Flat, leaf-like, photosynthetic asparagus stem.

What two processes are regulated by guard cells (stomata)?

• Gas exchange

• Water evaporation

Spine

Modified lead that reduces surface area and water loss & protects from herbivores (cactus)

Thorn

Modified stem that comes from axil of woody plants

Prickle

Outgrowth of epidermis (rose)

Explain why leaves of many trees exhibit a variety of colors before dropping off in the fall.

Leaves exhibit a variety of colors because the trees are preparing for a dormant season so the chlorophyll breaks down and the other pigments are revealed so that the tree can utilize the leaves’ nutrients.

What kind of root system do monocots have?

A fibrous root system.

What can develop from the pericycle?

Lateral (branch) roots and part of the vascular cambium.

Propagative Roots

Adventitious buds on roots develop into suckers (quaking aspen, fruit trees)

Aerial Roots

Orchids, corn, ivies

Contractile Roots

Pull the plant deeper into the soil (lily bulbs, dandelions)

Buttress Roots

Stability in shallow soil (tropical trees)

Mycorrhizae

Fungi that form a mutualistic association with plant roots.

Indeterminate Growth

Where new tissues are added indefinitely, season after season.

Apical Meristems: Protoderm

Gives rise to epidermis

Apical Meristems: Procambium

Produces primary xylem and phloem

Apical Meristems: Ground Meristem

Produces pith + cortex (parenchyma cells)

Heartwood

Older, darker wood in center

Sapwood

Lighter, still-functioning xylem. Closest to cambium.

Softwood

Wood conifers - no fibers or vessel elements

Hardwood

Wood of dicot trees

Dendroclimatology

The science of determining climate history by examining annual growth rings of trees.