Plants 2 (transport and reproduction

Question 1

What are the 3 techniques by which plants move water?

Answer 1

Root pressure, cohesion and transpiration

Question 2

What are the two factors that affect the movement of water into plant cells

Answer 2

Relative solute concentration

Physical pressure exerted by plant’s cell wall as cell fills w water

Question 3

What occurs when cellular pressure equals or exceeds osmotic pressure?

Answer 3

Net movement of water into the cell stops or reverses.

Question 4

What is water potential?

Answer 4

Water potential is the sum of cellular pressure and osmotic pressure

Water moves from higher water potential to lower water potential

Question 5

What is cohesion?

Answer 5

Intermolecular bonding between like molecules

Question 6

What is adhesion?

Answer 6

Bonding between unlike things

Question 7

What is surface tension?

Answer 7

Amount of force required to disrupt a surface of a liquid

Question 8

What happens when adhesive forces exceed cohesive ones?

Answer 8

Concave/meniscus shape U

Question 9

What happens when cohesive forces exceed adhesive ones?

Answer 9

Convex Shape N

Question 10

What are the two fates of water and minerals when uptaken by the epidermis?

Answer 10

1) Travelling through the cytoplasm of the epidermal cell to an adjacent cortex cell via plasmodesmata (symplast route)

2) Passing through the hydrophilic cell walls of epidermal cells and along a continuum of cell walls in the cortex. In other words, via walls (apoplast route).

Question 11

Where is the casparian strip located? What does it do?

Answer 11

The casparian is a waxy layer on the endodermis that seals off the apoplast route of entry into the stele.

Only way to bypass casparian strip is symplast route (forcing minerals and water to cross into the plasma membrane of the endodermis)

Question 12

What do the endodermis and parenchyma cells do in the stele?

Answer 12

Actively transport mineral ions lowering water potential inside the vascular bundles

Difference in water potential between stele and cortex allows water to flow into vascular tissue

Question 13

What is root pressure?

Answer 13

It is an upward push of fluid (sap). This occurs in the xylem when the buildup of water causes the sap to rise.

Root pressure alone is not sufficient to raise water up to the leaves of trees. ~6 to 10 feet

Question 14

What is transpiration? Where does it occur?

Answer 14

The evaporative water loss from an aerial portion of a plant. Occurs at stomata.

Question 15

How does transpiration contribute to water movement?

Answer 15

1) Transpiration occurs
2) Water coating mesophyll cells takes its place
3) Film of water coating mesophll cells forms a meniscus (adheres to the hydrophilic cell walls)
4) Film of water is under negative pressure thus creating a pull known as transpirational pull

Basically transpiration leads to adhesion to the xylem!

Question 16

How do we demonstrate transpiration in the lab?

Answer 16

A potometer

Question 17

How is transpiration regulated? What is uptaken and released at the stomata?

Answer 17

Transpiration is regulated by guard cells that flank the stomata

Water vapor released and co2 can be taken in

Question 18

How do guard cells regulate the size of the stomata? What ion fluctuates?

Answer 18

K+ change changes the shape of hte guard cells. Influx of water causes guard cells to lengthen thus opening the stomata bc of an increase in cellular pressure

Migration of ions out of the guard cells into surrounding tissue causes cell to lose water (osmosis) and shrink

Question 19

Where do the gametophytes of the (male/female plants) develop?

Answer 19

Male gametophytes develop within the anthers of the flower. The anthers produce pollen (immature male gametes)

Female gametophytes develop within the ovaries of the flower

Question 20

Life Cycle of flowering plants (How many generations? What kind of ploidy in each?

Answer 20

Regularly alternating sequence of 2 generations

Sphorophyte(mature plant body - diploid organism) produces haploid cells by meiosis, then these haploid cells go through mitosis to form megaspores and microspores

Gametophyte (micro and megaspores) by mitosis and cellular differentiation form gametophytes that contain true gametes (sperm and eggs). Fertilization leads to a diploid zygote that then becomes a mature sporophyte

Question 21

What develops as a result of fertilization of a male and female gamete in angiosperms? (How is this beneficial to the organism)

Answer 21

Pollen (immature male gametes) gets carried by wind to a female ovary.

Fertilization leads to the production of an embryo contained within a seed. Seed remains within ovary and develops into a fruit. Fruits get eaten by an animal and the animal shits seeds in different locations!

Question 22

What does the Stamen (male reproductive )consist of? (two things)

Answer 22

An anther (where pollen is produced) is attached by a stalk

Question 22

What are factors that trigger the transition between vegetative shoot growth (self-renewing) to determine (terminal ) growth within apical meristem tissue?

Answer 22

Environmental signals, such as the length of day and tissue hormones

Question 23

What are the four organs attached to the receptacle (part of the shoot(stem))?

Answer 23

Sepals, petals, stamens and carpels are attached to the receptacle

Stamen (male) and carpels (female) are reproductive organs

Petals and sepals (non-reproductive) are used to attract pollinators and protect reproductive structures

Question 24

What does the Carpel (female reproductive )consist of? (three things)

Answer 24

The carpel (in the middle of the receptacle) has a bulbous ovary with ovules, a style (which is like a stalk), stigma (end of the stalk that receives pollen)

Question 25

What do megasporocytes in the ovaries (female) do?

Answer 25

1) Diploid megasporocytes undergo meiosis to produce haploid megaspores.

2) The haploid megaspores then undergo mitosis to form an embryo sac (female gametophyte). Embryo sac has seven cells and eight nuclei.

Question 26

What do microsporocytes in the stamen (male reproductive) do?

Answer 26

1) Diploid microsporocytes undergo meiosis to form haploid microspores.
2) The microspores undergo mitosis to form two cells: generative cells (produce two sperm) and a tube cell (produces a pollen tube)

Both of these cells (generative and tube) form a pollen grain

Question 26

Steps of pollination/double fertilization (5 steps)?

Answer 26

1) Pollen grain is transported to the stigma (tip of the carpel) by wind or animal

2) Pollen grain absorbs water from stigma and germinates. The goal of the nucleus of the tube cell is to direct production of a pollen tube that grows down the style towards the ovary

3) As pollen tube grow, generative nucleus undergoes mitosis to produce two sperm

4) Pollen tube penetrates ovule and sperm is released into the ovule. One sperm and one egg produce a diploid zygote. The other sperm fertilizes a large cell central to the embryo sac that contains two nuclei (called polar nuclei) forming a food-storing tissue called endosperm

5) Double fertilized ovule develops into a seed (cotains zygote and endosperm). Ovary in which seed is contained becomes fruit.

In other words, generative cell two sperm; one for ovule forming zygote, and one for large cell to form food-storing endosperm