Plant Responses and Growth TEST

A plant stem that grows toward light is an example of a

• negative thigmotropism

• negative gravitropism

• positive phototropism

• positive gravitropism

To which 3 stimuli do plants respond?

• water

• light

• touch

• gravity

• soil conditions

When chlorophyll in leaves breaks down

• photosynthesis begins

• red pigments disappear

• yellow and orange pigments become visible

• the plant becomes very active

Irises and lettuce flower when nights are shorter than a critical length. They can be described as _______.

• short-day plant

• long-day plant

• dormant plants

• day-neutral plants

Chemicals produced by a plant that control its growth and developement are called ________.

• hormones

• sugar

• minerals

• proteins

A plant's roots grow away from a rock they hit in the soil. This is an example of a _________ thigmotropism.

• positive

• negative

___________ speeds up that rate at which a plant`s cells grow and controls a plant's response to light

• Chlorophyll

• Auxin

• Hormone

The chritical nighth length for a certain plant is 10 hours. This plant will flower only when nights are ______ than 10 hours-.

• shorter

• longer

• smaller

A plant adaptation that helps its survive freezing temperatures and lack of liquid water is

• dormancy

• phototropism

• photoperiodism

• gravitropism

The blooming of poinsettias in winter and irises in spring is an example of

• phototropism

• photoperiodism

• thigmotropism

• gravitropism