Plant Responses and Growth

EQ: How do plants respond to stimuli and hormones?

Tropisms

• A plant’s growth response toward or away from a stimulus– Thigmotropism - Touch– Phototropism - Light – Gravitropism - Gravity

EQ: How do plants respond to stimuli and

hormones?

Positive Tropism

• A plant growing toward a stimulus

EQ: How do plants respond to stimuli and hormones?

Negative Tropism

• A plant growing away from a stimulus

http://plantsinmotion.bio.indiana.edu/plantmotion/movements/tropism/gravitropism/gravi1/gravitrop.html

EQ: How do plants respond to stimuli and hormones?

Plant Hormones

• Hormone – a chemical that affects how a plant grows and develops– Control tropisms– Germination– Formation of plant parts– Shedding of leaves– Development of fruit

EQ: How do plants respond to stimuli and

hormones?

Plant Hormones• Auxin –

– Speeds up plant growth

– Controls plant’s response to light

EQ: How do plants respond to stimuli and hormones?

Life Spans of Angiosperms

• Annuals – flowering plants that grow, flower and die in a single year

• Biennials – complete life cycle in two years– 1st year germinate, grow roots and very short

stems and leaves– 2nd year grow new stems and leaves, produce

fruit

• Perennials – live longer than two yearsEQ: How do plants respond to stimuli and

hormones?

Class Work and Homework

• Fill In – What did I learn– Confused– Say

Read pages A164 – A166

Questions 1-4 A 166

EQ: How do plants respond to stimuli and hormones?