Ch 14

Question 1

Morphogenesis

Answer 1

generation of the shape of the plant and its various organs

Question 2

Differentiation

Answer 2

an increase in complexity as some cells become different from each other

Question 3

Polarity

Answer 3

having two different ends, usually a shoot/root polarity or a petiole/leaf tip polarity

Question 4

Hormone

Answer 4

a chemical that is produced by one part of a plant, often in response to a stimulus, and then is transported to other parts and induces responses in appropriate sites

Question 5

Satoliths

Answer 5

a type of starch grain that is so dense it sinks to the bottom of a cell’s cytoplasm, indicating the direction of gravity

Question 6

Light

Answer 6

• photosynthesis
• direction or gradient of light which allows a plant to grow and orient its leaves toward sunlight which increases light availability for photosynthesis
• duration of light/length of day provides info about the time of year/season; needs to have enough time to be dormant

Question 7

Gravity

Answer 7

• gravity causes weight stress so needs enough fibers to support its weight; bent from flooding or slipping from a hillside change growth to upright again
• roots know to grow down for nutrients and minerals and shoots grow up for photosynthesis, pollination and seed distribution
• force of gravity exerted on plant organs changes as the weight supported by the organ changes; if fruit like an apple develop must be able to support that with extra fibers

Question 8

Touch

Answer 8

• plants grow around and against objects when they come into contact with them
• thick bark can be produced if branches rub against stone or another branch
• tendril growing around an object is beneficial for support; fly touch a venus fly trap it closes
• different plants respond in different ways to contact depending on the plant

Question 9

Photoperiod

Answer 9

day length; the period of time that uninterrupted light is present

Question 10

Critical night length

Answer 10

the length of darkness that must be exceeded by short-day periods, or not exceeded by long-day plants, for flowering to be initiated

Question 11

Short day plants

Answer 11

a plant that is induced to flower by nights longer than the critical night length

Question 12

Long day plants

Answer 12

a plant that is induced to flower by nights shorter than the critical night length

Question 13

Endogeneous Rhythms

Answer 13

a rhythm generated entirely within an organism whose periodicity is not maintained by an external rhythm; certain aspects of their metabolism cycle is controlled by internal factors by an internal clock

Question 14

Entrain

Answer 14

the resetting of an endogeneous rhythm by an exogeneous stimulus

Question 15

Circadian rhythm

Answer 15

an endogeneous rhythm whose period is approximately 24 hours long

Question 16

ABC model of flower organization

Answer 16

three fundamental genes ABC interact to control the basic aspects of flower organization; Gene A affects the outermost, lowest region of a flower shoot apical meristem, gene C controls the uppermost, central region and gene B partially overlaps the other two