Review Questions for Botany Ch. 5,6,7,8

Distinguish between a tiny root and a root hair. What is the function of a root hair?

A root or tiny root is a multicellular organism with multiple tissue layers and other types of roots. Root hairs absorb water and minerals and adhere tightly to soil particles and are not separate cells

What is the difference between parasitic roots and mycorrhizae?

Parasitic roots are adventitious roots from the nodes of these plants penetrate into the hot tissue and enter into its conducting tissue to acquire nutrition, mycorrhizae is a symbiotic association between a fungus partner and roots of higher plants that benefits both the fungus and roots.

If you were shown cross sections of a young root and a young stem from the same dicot plant, how could you tell them apart?

When looking at a stem in cross section you will be able to determine that it is a stem and not a young root by the type of tissue present and not having an endodermal layer is the major clue.

What is the function of the root cap, and from which meristem does it originate?

The root cap is a protective cap of live parenchyma cells. It is produced by the apical meristem behind it. Root cap cells produce a slimy lubricant (mucilage or mucigel).

How do endodermal cells differ form other types of cells?

Endodermal cells differ from other cells in the root in that they

a. lack a symplast region.

b. are nonselective with regard to solute uptake.

c. have a high rate of water transport.

d. are completely surrounded by a waxy layer.

e. prevent the apoplastic movement of water and ions.

Thus, water must pass through the selectively permeable plasma membrane of the endodermal cells before it reaches the vascular system.

Where do branch roots originate?

Branch roots arise in the pericycle (a cylinder of parenchyma cells lying just inside the endodermis).

List some spices and drugs obtained from roots.

Sassafras, sarsaparilla, licorice, and angelica, are obtained from roots.

How is soil formed?

What does the solid portion of soil consist of?

What are the pore spaces between particles filled with?

Soil is formed though the interaction of climate, parent material, topography, vegetation, and living organisms. The solid portion of soil consists of minerals and organic matter.The pore spaces are filled with air or water.

What is the function of bud scales?

They protect the more delicate, inner, foliage leaves from drying up, from damage by birds, insects, fungi etc. and, to some extent, from extremes of temperature.

How can you tell the age of a twig?

Counting the number of groups of bud scale scars on a twig can tell one how old the twig is because the bud scales of a terminal bud leave tiny scars around the twig when they fall off in the spring.

Distinguish among procambium, vascular cambium, and cork cambium.

The procambium produces only primary xylem and phloem. Vascular cambium arises later and adds secondary xylem and phloem to the vascular bundles. Cork cambium arises within the cortex and produces box-like cork cells, which become impregnated with suberin.

How can you tell, when you look at a cross section of a young stem, whether it is a dicot or a monocot?

Monocot and dicot stems differ in the arrangement of their vascular system. In monocot stems, the xylem and phloem are paired in bundles, with bundles dispersed throughout the stem. In herbaceous dicot stems, the vascular system makes a ring, with the phloem to the exterior and xylem to the interior.

An Irish or white potato is a stem, but a sweet potato is a root. How can you tell?

All stems have nodes, internodes, and axillary buds; these features distinguish them from roots and leaves, which do not have them. In Irish or white potato plants, several internodes at the tips of stolons become tubers. The "eyes" of the potato are actually nodes. Each eye consists of an axillary bud in the axil.

Distinguish among corms, bulbs, and tubers.

Corms resemble bulbs, but differ from them in being composed almost entirely of stem tissue. Example of this are gladiolus plants.

Bulbs are large buds surrounded by many fleshy leaves, with a small compressed stem at the lower end. Onions are an example of bulbs.

Tubers function in underground storage. An example of a tuber is an "Irish potato."

What differences are there between sapwood and heartwood?

Older, darker wood at the center is called heartwood, while the lighter, still-functioning xylem closest to the cambium is called sapwood.

Leaves have no secondary xylem and phloem. Why not?

Leaves are meant to last for only a short time, even evergreen leaves only last for a couple of years. Secondary xylem and phloem require a good amount of energy to produce so it would be wasted on leaves. Secondary xylem serves a large structural function, especially in trees. Leaves don't need that structural support

Define transpiration, guard cells, mesophyll, venation, glands, and compound leaf.

Guard cells- control stomatal opening and contain chloroplasts. They regulate gas exhange, and evaporation of water.

Mesophyll- Two distinguishable regions: Palisade mesophyll may contain more than 80% of a leaf's chloroplast. Spongy mesophyll contains loosely arranged parenchyma cells with air spaces and some chloroplasts.

Venation- the arrangement of veins in a leaf.

Glands- depressions, protuberances, or appendages either directly on the leaf surface or on the ends of hair. Glands often secrete sticky substances.

Compound leaf- The blade is divided into leaflets. Has a single axillary bud at its base, with the leaflets having no buds.

How can one distinguish between the upper and lower epidermis in most leaves?

Typically, most of the stomata are located in the lower epidermis.

What is the function of bundle sheaths?

Thick-walled parenchyma cells that surround the vascular bundles, which consist of xylem and phloem. They give structure to xylem and phloem.

How do leaves in shaded areas differ from leaves in sunlit areas on the same plant?

Leaves in the shade are thinner and have fewer hairs than leaves on the same tree exposed to direct light. And because they receive less total light need for photosynthesis, they tend to be larger than their counterparts in the sun.

What leaf modifications are associated with dry areas, wet areas (e.g., lakes), climbing, and reproduction?

Dry areas have leaves that are thick and leathery with few stomata and/or sunken stomata.

Wet areas have tendrils, which are modified leaves that curl around more rigid objects helping the plant to climb or support weak stems.

Why do leaves turn different colors in the fall?

Leaves change color as green chloroplast pigments break down, revealing pigments of other colors, and different pigments consisting of anthocyanin (red/ slight blue color) and betacyanin (red color) accumulate in cell vauoles.

Define calyx, corolla, receptacle, peduncle, pedicel, pistil, filament, ovary, and carpel.

Calyx- the sepals of a flower are collectively called the calyx.

Corolla- the petals are collectively called the corolla.

Receptacle- the expanding tip of a peduncle or pedicel to which various parts of a flower are attached.

Peduncle- the stalk of a solitary flower or the main stalk of an inflorescence.

Pedicel- the individual stalk of a flower that is part of an inflorescence.

Pistil- consists of stigma, style, and ovary.

Filament- a semi-rigid stalk portion of a stamen

Ovary- the enlarged basal portion of a pistil that contains ovule/ ovules and usually develops in to a fruit.

Carpel- an ovule-bearing unit that is part of a pistil.

Indicate the features by which dicots are distinguished from monocots.

Dicots

• seed with two cotyledons (seed leaves)

•flower parts mostly in fours or fives or multiples of four or five

•leaf with a distinct network of primary veins

•vascular cambium, and frequently cork cambium, present

•vascular bundles of stem in a ring

•pollen grains mostly with three apartures

Monocots

•seed with one cotyledon (seed leaf)

•flower parts in threes or multiples of three

•leaf with more or less parallel primary veins

•vascular cambium and cork cambium absent

•vascular bundles of stem scattered

•pollen grains mostly with one aparture

What is the difference between a fruit and a vegetable?

A fruit is an ovary and its accessory parts that has developed and matured and it usually contains seeds. So-called vegetables (tomatoes, string beans, cucumbers, squares) are really fruits.

True vegetables can consist of leaves (e.g., lettuce, cabbage) leaf petioles (e.g., celery), specialized leaves (e.g., onion), stems (e.g., white potato), roots, stems, flowers and their peduncles (e.g., broccoli), flower buds or other parts of a plant.

What causes an ovary to develop into a fruit?

Fertilization usually indirectly determines whether ovaries develop into fruits. More specifically, pollen grains may initiate fruit development.

What are the various parts of a fruit?

Exocarp (skin)

Endocarp (inner boundary around seed(s))

Mesocarp (fleshy tissue between exocarp and endocarp)

All three regions are collectively called the Pericarp.

Distinguish among simple, aggregate, and multiple fruits.

•Simple fleshy fruits develop from a flower with a single pistil.

•Aggregate fruits are derived from a single flower with several to many pistils. (rasberries, strawberries)

•Multiple fruits are derived from several to many individual flowers in a single inflorescence. (pineapples, figs)

Distinguish among achenes, grains, samaras, and nuts.

These are indehiscent and therefore they are dry fruits that do not split at maturity.

Achenes- sunflower; attached to its surrounding pericarp

Nut- acorn; one-seeded fruits that are larger and the pericarp is harder and thicker than achene.

Grain- corn; pericarp is tightly united with seed and can't be separated from it.

Samara- maple; pericarp surrounding seed extends out in the form of a wing, which aids in dispersal.

What adaptions do seeds and fruits have for dispersal by water and animals?

Water dispersal - some fruits contain trapped air (bouyant seeds). Seeds can have inflated sacs that enable them to float.

Animal dispersal - seeds pass through digestive tract, fruits and seeds catch in fur/ feathers, oils can attract ants.

Define plumule, after-ripening, radicle, and vivipary.

Plumule- embryo shoot

After-ripening- seed will not germinate after the fruit has dropped until embryo has developed.

Radicle- stem tip developing into a root.

Vivipary- the growth of the embryo while the seed and fruit are still on the plant. Young derives nutrient from the parent.