plant physiology

Question 1

what are the two systems of plant organization?

Answer 1

shoot system and root system

Question 2

what is a shoot system?

Answer 2

above ground, involves stems, leaves, flowers, and fruit

Question 3

what is a root system?

Answer 3

below ground, the roots

Question 4

how many tissue systems are there in plants?

Answer 4

three!

Question 5

how many tissue systems do the organs contain?

Answer 5

they contain all three tissue systems.

Question 6

what is the function of plant roots?

Answer 6

they anchor to the ground, absorb minerals and water, and store carbohydrates and other reserves

Question 7

what are root hairs and what is the purpose?

Answer 7

they are thin extensions of root epidermal cells and are found primarily near the tip of elongated roots. they increase the surface area which increases the amount of minerals and water the roots can absorb!

Question 8

what are stems and what is the purpose?

Answer 8

stems are the plants organs bearing leaves and buds. they elongate and orient shoot (the part of the plant that is above ground!) to maximize photosynthesis. they also elevate reproductive structures – increase pollen and seed dispersal.

Question 9

what are leaves and what is the purpose?

Answer 9

they are the main photosynthetic organ in vascular plants, they capture light and are involved in gas exchange

Question 10

what is the dermal tissue system? what are some examples

Answer 10

the outer protective covering of a plant! in nonwoody plants there is the epidermis and the cuticle. in woody plants there is the periderm which replaces the epidermis.

Question 11

what is the epidermis?

Answer 11

a type of dermal tissue system found in nonwoody plants, it is a single layer of tightly packed cells

Question 12

what is the cuticle?

Answer 12

a type of dermal tissue found in nonwoody plants, it is a waxy coating that prevents water loss

Question 13

what is the periderm?

Answer 13

a type of dermal tissue system found in woody plants, it is simply bark and replaces the epidermis

Question 14

what are the functions of dermal tissue?

Answer 14

protect the plant, helps with the absorption of water and minerals at root hairs, reduces water loss, reflects sunlight, regulate gas exchange with specialized cells called guard cells

Question 15

what are guard cells?

Answer 15

specialized cells in shoots, they surround the stomata, regulate gas exchange

Question 16

what is the ground tissue system?

Answer 16

consists of most of the plant and includes cells specialized for storage, photosynthesis, support, and short distance transport

Question 17

what is the vascular tissue system?

Answer 17

transports materials throughout the plant body and provides mechanical support. there are two types of tissues: xylem and phloem.

Question 18

what is the xylem?

Answer 18

a type of vascular tissue system that conducts H2O and dissolved minerals upwards from roots

Question 19

what is the phloem?

Answer 19

a type of vascular tissue system that transports sugars from wehre they are made (mostly leaves) to where they are needed (typically the roots and sites of growth).

Question 20

how does water move through the xylem?

Answer 20

1. soil
2. root tissue
3. root xylem
4. stem xylem
5. leaf xylem
6. leaf mesophyll
7. stomata
8. atmosphere

Question 21

what is the cohesion tension hypothesis?

Answer 21

during photosynthesis the stomata opens to take in CO2 and H2O is released (a process called transpiration). transpiration creates tension or a suction, which pulls water up from the roots. the xylem tube acts as a straw and carries the water and nutrients.

Question 22

how does the phloem conduct dissolved sugar?

Answer 22

the process is known as translocation because the movement can occur bidirectionally (up or down). sugars are moved from sources (areas w/ excess sugar, like leaves) to sinks (areas of storage or metabolism, like the roots).

Question 23

what is the pressure flow hypothesis?

Answer 23

an explanation for movements of sugars in phloem, this suggests that translocation occurs via pressure gradient. at the source there is a high amount of pressure (sugar loaded into phloem) while at the sink there is low pressure (sugar removed from phloem).

Question 24

what is the plasmodesmata?

Answer 24

cytoplasmic connections that allows molecules and ions to pass between cells. it is very important for plant transport.

Question 25

what are meristems and what do they have to do with plant growth?

Answer 25

meristems drive indeterminate growth in plants (occurs throughout life of plant). this growth is sustained by perpetually dividing unspecialized cells found in meristems. these cells continuously add new cells which allows the plant to increase in length through primary growth, a process common to all plants

Question 26

what is first degree growth?

Answer 26

all plants have first degree growth, it is where the length increases by adding more cells

Question 27

what is second degree growth?

Answer 27

this only occurs in woody plants, it is a process where the girth (circumference) of plants increases

Question 28

what are plant hormones?

Answer 28

they are also known as plant growth regulators
- organic compounds that act as chemical messengers that control specific physiological responses in plants
- active at very low concentrations and can have a variety of effects
- hard to determine the specific cause of a particular effect because they often interact with one another.
- can be natural compounds (produced byt eh plant) or synthetic (created in labs).

Question 29

what are auxins and what is their function?

Question 30

what are tropisms?

Answer 30

directional growth responses to environmental stimulus–often due to hormones! positive means it grows towards the stimulus, negative means it grows away from stimulus.

Question 31

what was darwins experiment with phototropism and grass seedlings? what was the conclusion?

Answer 31

darwin exposed the grass seedlings to light from one direction.
- when the tip was shielded/removed -> NO bending occurred
- when the shield was transparent -> bending occurred
- when the shield was below the tip -> bending occurred
the seedling tip was responsible for light sensing
theorized/postulated that the signal was transmitted from the tip to the elongated region

Question 32

what was the boysen jensen experiment?

Answer 32

exposed grass seedlings to light from one direction separated the tip was gelatin (permeable) -> bending occurred
separated with mica (impermeable) -> no bending

Question 33

what is phototropism?

Answer 33

it is the growth response of plants to light. when exposed to light, the plant produces auxin. auxin moves laterally from the light to the shaded region of the plant as well as down the stem. this uneven distribution triggers cell alongation on the shaded side which causes the plant to bend towards the light source.

Question 34

what are cytokinins?

Answer 34

plant hormones that affect cell division and differentiation. they are produced in actively growing tissue, like roots, embryos, fruit, etc. they stimulate cytokinesis

Question 35

how does cytokin act with auxin?

Question 36

what is ethylene?

Answer 36

unique plant hormone that plays a crucial role in ripening fruits by triggering the process by which fruits soften and change color. Also induces a triple response to mechanical stress when a growing shoot encounters an obstacle. the triple response includes slow elongation, thicken stem curve, and causes the shoot to grow horizontally.