Labs 1-3

Question 1

What two means of dispersal have plants evolved?

Answer 1

Plants have evolved two means of dispersal: spores or seeds

Question 2

How do the seedless plants disperse?

Answer 2

• They disperse as spores
• The seedless plants include the bryophytes (liverworts, hornworts, mosses), the lycophytes (club mosses, quillworts Selagineslla), Psilotum, horsetails, and ferns

Question 3

What are spores?

Answer 3

Spores are thick-walled single cells that are typically wind dispersed

Question 4

How do the seed plants disperse?

Answer 4

• they disperse as seeds
• each seed includes an embryonic plant supplied with stored food
• the seeds are dispersed by various means, depending on the design of the seed

Question 5

What is in a seed?

Answer 5

• each seed includes an embryonic plant supplied with stored food
• the seeds are dispersed by various means, depending on the design of the seed

Question 6

Gymnosperms

Answer 6

• the naked-seeded plants that include the conifers, ginkgo, cycads, and several others
• “gymnos” =naked
• “sperma” =seed
• the seed is naked because the ovule from which it developed was naked (not enclosed in tissue)

Question 7

Angiosperms

Answer 7

• the flowering plants
• seed is enclosed because the ovule from which it developed was enclosed within the ovary of the flower’s pistil
• (Greek: angeion = container; the seeds are contained, enclosed within a fruit, although at maturity the fruit may split open to release the seeds)

Question 8

Ovules

Answer 8

• produced by all seed plants
• develop into seeds after fertilization
• the structure contained within the ovary that gives rise to the female gametophyte and, when fertilized and mature, a seed
• embedded within the tissue of each ovule is an egg cell; the egg cell is located near a tiny opening in the ovule called the micropyle (Greek: mikros = small; pyle = gate)
• Pine: ovules on the scales of young female cone
• Flower: ovules within the ovary

Question 9

What do all seed plants produce?

Answer 9

Ovules and pollen

Question 10

Pollen

Answer 10

• Pine: produced by separate male cones
• Flower: produced by anthers
• pollen grains contain sperm cells, after a sperm fertilizes the egg cel in an ovule, the ovule matures into a seed
• (Latin: pollen= fine flour)

Question 11

What are the parts of a seed?

Answer 11

• Seed coat
• embryo
• nutritive tissue

Question 12

Seed coat

Answer 12

• a protective covering that developed from the outer layers of the ovule and is thus material from the mother plant
• the seed coat may have structural modifications to assist in seed dispersal; for example, many pines produce “winged” seeds, the wing being a dry extension of the seed coat that aids in gliding through the air

Question 13

Embryo

Answer 13

• the offspring plant that developed from the fertilized egg

- attached to the embryo are one or more fleshy, nutrient-rich structures called cotyledons

Question 14

Cotyledons

Answer 14

• fleshy, nutrient-rich structures
• attached to the embryo are one or more of these
• gymnosperms tend to have several cotyledons per embryo

Question 15

What two groups are angiosperms divided into?

Answer 15

• Monocotyledons or monocots (one cotyledon per embryo)

- and dicotyledons or dicots (two cotyledons per embryo)

Question 16

Monocotyledons (monocots)

Answer 16

One cotyledon per embryo

Question 17

Dicotyledons (dicots)

Answer 17

Two cotyledons per embryo

Question 18

nutritive tissue

Answer 18

• Stored food

- provides the germinating seedling with energy for a brief period

Question 19

Endosperm

Answer 19

The nutritive tissue in angiosperm seed

Question 20

Hilum

Answer 20

• Belly button

- The point at which the seed was attached to the inside of the ovary

Question 21

Micropyle

Answer 21

the small opening or “gate” through which the pollen tub entered the ovule in order to deliver the sperm to the egg

Question 22

Scarification

Answer 22

Rubbing seeds between sandpaper or soaking them in acid

Question 23

Stratification

Answer 23

Placing seed between moist layer of sand or paper towels in a refrigerator

Question 24

Imbibition

Answer 24

a passive process that swells the seed

Question 25

Cellular respiration

Answer 25

An enzymatic process that breaks sown materials

Question 26

Dormancy

Answer 26

defined as the failure to germinate even under optimum condition of moisture, temperature and aeration

Question 27

P(r)

Answer 27

- does not germinate | - absorbs red light and changes to P(fr)

Question 28

P(fr)

Answer 28

- ready to germinate when in this form | - when absorbing far red light turns back to P(r)

Question 29

Gibberellic Acid (GA)

Answer 29

Can be used as a substation for light in germination of seeds