Plant growth & Differentiation

Question 1

Growth

Answer 1

the prices of increasing in size

Question 2

Differentiation

Answer 2

the process of cell specialization to allow for specific(xylem cells instead of ground cells)

Question 3

Types of growth

Answer 3

• Apical meristems
• Lateral meristems

Question 4

Apical meristems

Answer 4

• plant tissue composed of actively dividing cells; repsonsibke for primary growth and located at the tip of the roots and shoots of a plant
• increases height of plant

Question 5

Lateral meristems

Answer 5

plant tissue consisting of actively dividing cells that produce secondary growth(increase width of plants)

Question 6

Primary growth

Answer 6

-increased length of plant shoot or root
-cells divide by mitosis
-increased number of cells
-cells elongate then differentiate
-differentiation depends on location of meristem - shoot becomes stems, leaves, reproductive organs

Question 7

Secondary growth

Answer 7

-only happens in woody species after first year
-secondary tissues produced
-ex vascular cambium, cork cambium

Question 8

Environmental factors affecting plant growth and differentiation

Answer 8

-Light
-Nutrients
-Temp
-Soil

Question 9

Light affecting plant growth

Answer 9

-any environment, the wavelength of light (light quality) that reach a plant will vary (differnt wavelengths at high noon vs evening)
-intensity of light and length of day also varies
-plant detects changes in light conditions using photoreceptors(detect light)

Question 10

Photoreceptors

Answer 10

detect changes in light and this signals to the plant to change its growth or development(germination, leaf dropping)

Question 11

Photoperiodism

Answer 11

plants response to changes in day length;
-Short day plants flower when the days are short(tulips)
-Long day plants fowler when there are 12h+ of day light(spinach)
-Day neutral plants aren’t affected by day length(roses, tomatoes)

Question 12

Nutrients affecting plant growth

Answer 12

-Plants make carbs, fats, and protiens from inorganic substances called macronutrients and micronutrients
-macronutrients: plant nutrients needed in large amounts such as N, P, K
-Deficiencies of macronutrients leads to symptoms(nitrogen of magnesium deficiency can lead to chlorosis)
-micronutrients: plant nutrients needed in small quantities such as B, Cl, Cu, Fe, Mn, molybdenum, Ni, Zn. These are needed for chlorophyll, synthesis, cell division, and enzyme production

Question 13

Temperature affecting plant growth

Answer 13

-Plants have optimal temp. range for cellular processes
-Temperature controls the opening and closing of stomata which helps control of transportation
-Timing of seed germination and flowering is affected by temperature
-Climate change is also having an effect. Every 1 degree can cause flowering to occur 5 days earlier. This can trick plants to flower before pollinators are available. If other plants are now flowering it can increase competition for pollinators

Question 14

Soil affecting plant growth

Answer 14

• 3 important roles:
  1. provides medium for roots to anchor;
  2. it retains water/nutrients;
  3. provides roots with air.
• soil that has too much sand can lose water quickly, clay holds onto too much water and doesn’t have many air spaced which can cause plants to drown
  -Soil must have humus: organic matter made up of decomposed organisms. Good for plants because it contains nitrogen

Question 15

Plant growth regulators

Answer 15

-Chemicals that allow plants to modify their growth and differentiation
-Signal plant cells to undergo particular changes(elongate to bend one direction)
-Tropism
-Phototropism
-Gravitropism
-Thigmotropism

Question 16

Tropism

Answer 16

a directional change in growth or movement in response to a stimulus. Plant will move to or away from the direction of the stimulus and this is hormone mediated

Question 17

Phototropism

Answer 17

a change in direction of a growing plant in response to light. Occurs due to factor released from the top of the plant. This allows for increased light exposure

Question 18

Gravitropism

Answer 18

a change in growth pattern in response to gravity( roots frown down, shoot grows up)

Question 19

Thigmotropism

Answer 19

a directional change in growth pattern in response to contact(vines wrap around the other trees)

Question 20

Nastic movements

Answer 20

-non directional movements which are independent of the direction of the stimulus
-Temporary and may take only a few seconds to occur
-Due to tugor pressure(water pressure inside plant) changes
-Plant will regain its original shape

Question 21

various plant growth regulators

Answer 21

-Auxins
-Gibberellins
-Cytokinins
-Ethylene
-Abscisic acid(ABA)

Question 22

Auxins

Answer 22

-Promotes cell division and elongation
-The cells in the shade have more auxin than those in the light which causes them to elongate and plant bends towards light

Question 23

Gibberellins

Answer 23

-Promote cell division, cell elongation and seed germination
-Used commercially to promote seed germination stimulates flowering and fruit production

Question 24

Cytokinins

Answer 24

-Prvent plant aging by inhibiting protien breakdown and stimulating
-Inhibits ethylene

Question 25

-Ethylene

Answer 25

-A gas produced by plants at various stages
-“Plant stress hormone” which protects to loose leaves during drought environmental stressors. It cashed plants to loose leaves during drought
-Stimulates aging of plants, fruit ripening, shoot and root growth and development, flower opening, leaf and fruit drop
-Producers have to ship fruit in well-ventilated trucks that contain ethylene-absorbing factors
-Ethylene sensitive plants like broccoli and cabbage have to be shipped separately from high ethylene producers like apples and bananas

Question 26

Abscisic acid

Answer 26

-Inhibit seed germination and plant growth
-Maintains dormancy in lead buds and seeds
*dormant plants are less susceptible to damage than actively growing plants
-Controls guard cells causing stomata to close to prevent loss of water when environment is dry which can help plants conserve water