13.1.1 Plant Development: Germination

Question 1

Plant Development: Germination

Answer 1

• Fruit is the mature ovary of a plant that functions in the protection and distribution of dormant seeds. Fruits aid in the distribution of seeds in many ways. For example, seeds can stick to the fur of animals, pass through the digestive system of animals, and be aerodynamically shaped for optimal dispersal by wind.
• Germination, the process by which the embryo emerges from the seed, consists of three major phases:
· imbibition
· growth of the radicle
· development of the shoot
• Primary meristems are embryonic tissues that allow for indeterminate growth. Protoderm, ground meristem, and procambium are three primary meristems that form the three major tissue systems in the plant body

Question 2

germination

Answer 2

• Germination begins when the seed undergoes imbibition, or the uptake of water. Water enters the seed and causes it to expand, rupturing the seed coat.
• Imbibition triggers enzymatic changes in the embryo,
  signaling it to proceed with growth and to use nutrients stored within the cotyledons. The radicle, which is the embryonic root, is the first structure to emerge from the germinating seed.
• The shoot then grows from the germinating seed and must break through the soil and emerge from the surface.

Question 3

hypocotyl

Answer 3

• In beans, a bend of the hypocotyl, called the hypocotyl hook, is pushed above ground by growth of the shoot. The hypocotyl hook then straightens out and pulls the cotyledons above ground.
• Notice in the diagram to the left that the cotyledons are above ground.

Question 4

epicotyl

Answer 4

• In peas, a bend at the epicotyl, called the epicotyl hook, is pushed above ground by growth of the shoot. The epicotyl hook then straightens out and raises the tip of the shoot above ground.
• Notice in the adjacent diagram that the cotyledons remain underground.

Question 5

coleoptile

Answer 5

• In corn and other monocots, the coleoptile, a sheath that encloses the embryonic shoot, pushes up through the soil to the surface. The tip of the shoot then grows up through the coleoptile above the surface of the ground

Question 6

three tissue systems

Answer 6

• Three tissue systems arise in the developing embryo. The procambium is a primary meristem that gives rise to
  vascular tissue. Vascular tissues conduct water and nutrients in plants.
• The ground meristem is a primary meristem that gives rise to ground tissue in plants. Ground tissue fills in the space between dermal and vascular tissues.
• The protoderm is the outer cylinder of primary meristem that gives rise to epidermal tissue. Epidermal tissue makes up the protective outer covering in plants.

Question 7

Monocots are able to break through the soil when they are germinating without damaging the apical meristem because of the

Answer 7

• coleoptile

Question 8

After germination, the ____________ of the embryo will give rise to the leaves.

Answer 8

• epicotyl

Question 9

Germination begins when

Answer 9

• the seed swells from the uptake of water.

Question 10

Which of the following conditions is almost always needed by seeds in order to break dormancy?

Answer 10

• imbibition

Question 11

Which of the following structures is the radicle?

Answer 11

• D

Question 12

Which of the following structures is referred to as the hypocotyl?

Answer 12

• C