Midterm 1

Question 1

What are the three principal tissue meristems that are laid down during plant embryogenesis?

Answer 1

1. Vascular Tissues (procambium)
2. Ground Tissues (ground meristem)
3. Epidermis (protoderm)

Question 2

What are examples of specialized tissues and cell types will ground tissue turn into in a leaf?

Answer 2

• mesophyll
• palisade cells
• spongy mesophyll cells

Question 3

What are examples of specialized tissues and cell types will vascular tissue turn into?

Answer 3

• xylem

- phloem

Question 4

What are the three categories of ground cell, cell types?

Answer 4

1. Parenchyma cells
2. Collenchyma cells
3. Sclerenchyma cells

Question 5

What are some features of parenchyma cells?

Answer 5

• thin and flexible cell walls
• living at maturity
• carry on most of the plant’s metabolic functions
• have the ability to differentiate into other cell types under special conditions during repair and replacement of organs after injury

Question 6

What are some examples of parenchyma cells?

Answer 6

• palisade mesophyll cells
• spongy mesophyll cells
• guard cells
• cortex
• pith

Question 7

What are some features of collenchyma cells?

Answer 7

• thicker primary cell walls (usually with uneven thickness, typically thicker in “corners”
• living at maturity
• role in support of herbaceous plants (“strings” of celery)

Question 8

What are the general features of sclerenchyma cells?

Answer 8

• thick secondary cell walls
• dead at functional maturity
• cannot increase in length- occur in parts of the plant which have quit growing in length

Question 9

What are the two types of sclerenchyma cells?

Answer 9

1. Fibers

2. Sclerids

Question 10

What are the features of fibers?

Answer 10

-long, slender cells with a more or less regular secondary cell wall

Question 11

What are the features of sclerids?

Answer 11

-shorter cells with an irregular shape

Question 12

What is the middle lamella?

Answer 12

pectin that glues cells together

Question 13

What are features of the primary wall?

Answer 13

• laid down first
• mostly cellulose
• resists internal turgor pressure (positive pressure)
• generating stiff cells

Question 14

What are features of the secondary wall?

Answer 14

• laid down in some cells
• mostly cellulose and lignin
• resists internal negative pressure (collapse_
• strong resistance to rot

Question 15

Generally how do plants take up water?

Answer 15

by negative pressure

Question 16

What do pits do?

Answer 16

provide cell wall free connections between cells

Question 17

What is the function of chloroplasts?

Answer 17

• chlorophyll pigment

- photosynthesis

Question 18

What is the function of chromoplasts?

Answer 18

-store pigments other than chlorophyll for recognition (petals, flowers)

Question 19

Where are chromoplasts primarily stored?

Answer 19

in plastids

Question 20

What are leucoplasts?

Answer 20

• non-pigmented plastids

- primarily in root and storage structures

Question 21

What are the three types of leucoplasts?

Answer 21

1. Amyloplasts
2. Elaioplasts
3. Proteinoplasts

Question 22

What do amyloplasts do?

Answer 22

• starch storage
• gravity sensing
• terpene biosynthesis

Question 23

What do elaioplasts store?

Answer 23

• oil

Question 24

What do proteinplasts store?

Answer 24

• protein

Question 25

What are functions of vacuoles?

Answer 25

- store water while concentrating surrounding cytoplasm - isolate harmful materials - store waste products - maintain internal hydrostatic pressure or turgor within the cell

Question 26

What does the plasmodesma allow intracellular movement of?

Answer 26

- water and other small molecules | - macromolecules such as proteins and mRNAs

Question 27

When is the primary plasmodesmata formed?

Answer 27

-during cell division

Question 28

When is the secondary plasmodesmata formed?

Answer 28

-later by enzymes digesting cell wall

Question 29

What is the plasmodesma?

Answer 29

-cytoplasmic connections between cells

Question 30

How can the plasmodesmata be closed?

Answer 30

-by synthesis of callose (sugar polymer) in the neck region

Question 31

How is the plasmodesmata reopened?

Answer 31

-by callose digestion

Question 32

Why is water status important?

Answer 32

-it is key for growth and photosynthesis

Question 33

How is surface tension in water created?

Answer 33

-the contractive tendency of water minimizes the interaction with air (that has weak cohesion between molecules)

Question 34

Why is evaporation in plants important?

Answer 34

-evaporation of water in leaf airspaces cools down the leaf, which is an important mechanism to cope with heat stress

Question 35

Why is the cohesion of water molecules important for long distance transport of water?

Answer 35

-results in high tensile strength and makes it able to resist tension and negative hydrostatic pressure

Question 36

What is osmosis?

Answer 36

-diffusion of fluid through a semi-permeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal concentration of fluid on both sides of the membrane