Organic Gardening Midterm Exam 1

Front 1

Describe how the photosynthesis/respiration balance is important for plant.

Back 1

In order for a plant to grow and develop properly, it must balance photosynthesis, respiration, and transpiration. Left to their own devices, plants do a good job or managing this intricate balance. If a plant photosynthesizes at a high rate, but its respiration rate is not high enough to break down the photosynthates produces, photosynthesis will either slow down or stop. On the other hand, if respiration is is much more rapid than photosynthesis, the lant won’t have adequate photosynthates to produce energy for growth. Hence, growth either will slow down or stop altogether.

Front 2

modified stems - crowns

Back 2

are compressed stems with leaves and flowers on short internodes.
(on strawberries, dandelions, and African violets)

Front 3

modified stems - stolons

Back 3

are fleshly or semiwoody, elongated, horizontal stems that often lie along the soil.

Front 4

modified stems - tubers

Back 4

Potato tubers, iris rhizomes, and tulip bulbs are underground stems that store food for the plant. Stems have nodes (unlike roots). In potato tubers the “eyes” are actually the stem’s nodes, and each eye contains a cluster of buds.

Front 5

modified stems - bulbs (tunicate)

Back 5

tunicate bulbs (daffodils, tulips, and onions) have a thin, papery covering, which actually is a modified leaf. It helps protect the bulb from damage during digging and from drying out once it is out of the soil.

Front 6

modified stems - bulbs (nontunicate)

Back 6

Nontunicate bulbs (lilies) do not have this papery covering. They are very susceptible to damage and drying out, so handle them very carefully.

Front 7

Name the primary and secondary macronutrients.

Back 7

Soil elements are called primary nutrients because they are used in relatively large amounts: they are nitrogen, phosphorus, and potassium. Calcium, magnesium, and sulfur are called secondary nutrients because they are used in moderate amounts. Collectively they are called macronutrients.

Front 8

How are the macronutrients absorbed into plant tissues?

Back 8

Most of the nutrients a plant needs are dissolved in water and then absorbed by its roots. In fact, 98 percent are absorbed from the soil-water solution, and only about 2 percent are actually extracted from soil particles.

Front 9

The five groups of hormones?

Back 9

gibberellins, auxins, cytokinins, abscisic acid, and ethylene

Front 10

gibberellins

Back 10

helps seeds and buds break dormancy, makes stems lengthen, influences flowering, control ripening. (Lec 4, p. 4)

Front 11

auxins

Back 11

promotes stem lengthening, synthetic auxins used in herbicides, indoleacetic acids (iaa) response to gravity and light.

Front 12

cytokinins

Back 12

promotes cell division, mostly in root and shoot merristems and maturing fruit, produced in the roots of mature plants and transported to the shoots, extend life of cut flowers, delays leaf death.

Front 13

abscisic acid

Back 13

causes the suspension of growth; promotes dormancy of buds and seeds, drought response.

Front 14

ethylene

Back 14

induces age responses, is a gas, used to ripen fruit.

Front 15

What are perfect/imperfect flowers?

Back 15

If a flower contains both functional stamens and pistles, it is called a perfect flower, even if it does not contain petals and sepals. If either stamens or pistles are lacking, the flower is called imperfect.

Front 16

Monoecious and dioecious plants?

Back 16

Monoecious plants have separate male and female flowers on the same plant (corn and peanuts). Some monoecious plants bear only male flowers at the beginning of the growing season, but later develop both sexes (cucumbers and squash). Dioecious plants have separate male and female plants (holly, ginkgo). In order to see fruit male and female plants must be grown close together.

Front 17

Stamen

Back 17

is the male reproductive organ. It consists of a pollen sac (anther) and a long supporting filament. This filament holds the anther in position, making the pollen available for dispersement by wind, insects, or birds.

Front 18

Pistle

Back 18

is the female reproductive organ. It generally is shaped like a bowling pin and is located in the flower’s center. It consists of a stigma, style, and ovary. The stigma is located at the top and is connected by the style to the ovary. The ovary contains eggs, which reside in ovules. If an egg is fertilized, the ovule develops into a seed.

Front 19

What are plant tropisms?

Back 19

Adjustment of plant growth toward or away from an environmental stimulus.

Front 20

Name the tree plant tropisms.

Back 20

geotropism, phototropism, thigmotropism

Front 21

Geotropism (stimulus is gravity)

Back 21

Roots tend to grow toward pull off gravity; shoots grow against it.

Gravitational field is sensed via position off statoliths (a type off amyloplast).

Auxin is involved in response; causes asymmetric cell elongation.

Front 22

Phototropism (stimulus is light)

Back 22

Change in growth in response to light.

Controlled by the flow of auxin produced in the plant tip.

Front 23

Thigmotropism (stimulus is contact with an object

Back 23

Growth in response to contact with a solid object.

Allows vines and tendrils to wrap around supports.

Cells on contact side elongate, causing stem to curl Auxin and ethylene may be involved.

Front 24

Short-day plants

Back 24

form flowers only when day length is less then about 12 hours. Many spring and fall flowering plants, such as chrysanthumums, poinsettias, and Christmas cactus, are in this category.

Front 25

Long-day plants

Back 25

form flowers only when day length exceeds 12 hours. Most summer flowering plants (rudbeckia, California poppies, and asters), as well as many vegetables (beets, radishes, lettuce, spinach, and potatoes) are in this category.

Front 26

Day neutral plants

Back 26

form flowers regardless of day length (tomatoes, corn, cucumbers).

Front 27

abscission

Back 27

Dropping of flowers, fruits, or leaves.

Front 28

senescence

Back 28

Sum total of processes that lead to death of a plant or some of its parts.

Factors that influence senescence:
- Decrease in daylight is recurring factor
- Wounds, drought, or nutritional deficiencies can also bring it about.

Front 29

dormancy

Back 29

A predictable period of metabolic inactivity.

Short days; long, cool nights trigger dormancy.

Experiments have shown that exposure to light blocks dormancy.

Front 30

vernalization

Back 30

Subjection of seeds or seedlings to low temperature in order to hasten plant development and flowering.

Front 31

What brings abscission about?

Back 31

Auxin production declines

Cells in abscission zone produce ethylene.

Enzymes digest cell walls that attach leaf or fruit to plant fruit to plant.

Front 32

apical meristems

Back 32

are the site of primary growth in a plant, and can be found at the root and shoot tips.

Front 33

lateral meristems

Back 33

vascular cambium and cork cambium cause lateral growth, which grows out the side of the plant Lateral meristems are responsible for secondary thickening, which is required by perennial plants that grow year after year, and need the structural support to continue doing so.

Front 34

Vascular tissue is divided into

Back 34

Xylem – dead cells for water transport

Phloem - live cells for sugar transport

Front 35

Terminal bud

Back 35

At the apex (tip) of a stem. Each branch has its own terminal bud.

Front 36

Axillary (lateral) bud

Back 36

located on the sides of a stem, and usually arise where a leaf meets a stem (an axil). In some cases an axil contains more than one bud.

Front 37

Adventitious bud

Back 37

occurring elsewhere. They may develop from roots, a stem, internode, the edge of a leaf blade or callus tissue at the end of a stem or root.

Front 38

Required for seed germination?

Back 38

often requires imbibation and oxygen as well as special temperature and light requirements.

Front 39

Describe how transpiration happens from root to leaf.

Back 39

When a leaf’s guard cells shrink, its stomata open, and water vapor is lost. In turn, more water is pulled through the plant from the roots. The rate of transpiration is directly related to weather stomata are open or closed. Stomata account for only 1 percent of a leaf’s surface but 90 percent of the water transpired.

Front 40

Explain how leaves are adapted for maximal photosynthesis.

Back 40

Leaves are usually thin
- High surface area-to-volume ratio
- Promotes diffusion of carbon dioxide in, oxygen out.

Leaves are arranged to capture sunlight
- Are held perpendicular to rays of sun
- Arranged so they don’t shade one another

Front 41

Monocots

Back 41

plant types – corn, lilies, onions, orchids, coconuts, bananas, and the grasses.

cotyledons – one seed leaf

leaves – often parallel veined. carbon dioxide in and oxygen out, arranged not to shade each other out and to capture the sun light,

vascular tissue – Xylem and phloem are paired in bundles, which are dispersed throughout the stem. is through out the ground tissue,

pollen - with single furrow or pore

floral part – in multiples of three

roots – fibrous

Front 42

Dicots:

Back 42

plant types - sunflowers, garden bean, roses, cucumbers, peas, pears, maples, and oaks.

cotyledons – two seed leaves

leaves - generally net veined. carbon dioxide in and oxygen out, arranged not to shade each other out and to capture the sun light

vascular tissue – Xylem and phloem form rings inside the stem. The phloem forms the outer ring, the xylem an inner ring. the ring of vascular bundles separate cortex from the pith

pollen – with three furrows or pores

floral part – in multiples of four or five

roots – tap root