Lecture 10-11-12

Question 1

What is the periderm?

Answer 1

Protective tissues that act as armour for the plant’s inner tissues from biotic and abiotic stress.

Question 2

What are lenticels?

Answer 2

They are the openings in the periderm.

Question 3

What is secondary growth? And what role does the vascular cambium play?

Answer 3

SG results from activity of vascular cambium, which arises from the pro-cambium in vascular bundles and in part from inter-fascicular parenchyma. Development of vascular cambium leads to secondary growth

Question 4

What is the relationship like between sieve elements and companion cells?

Answer 4

They are derived from the same mother cell and maintain extensive cytoplasmic connectivity.

Question 5

What is the origin of lateral roots?

Answer 5

The pericycle gave rise to lateral roots.

Question 6

What is the Quiescent zone in a root?

Answer 6

It is a rarely dividing pool of stem cells within the root apical meristem (RAM).

Question 7

What is the “Casparian Strip” ?

Answer 7

Thickenings with the anticlinal walls of endodermal cells which are waterproof. This then breaks the apoplastic flow of water in the cell and forces dissolved substances to pass through.

Question 8

What are Bulliform cells?

Answer 8

Thin walled cells of the grass epidermis that are larger and more inflated than neighbouring cells.

Question 9

What are Statocytes and Statoliths?

Answer 9

Statocytes are specialized cells that contain Statoliths, they are involved in gravity perception. Statoliths are starch grains which are suspended against cytoskeletal elements.

Question 10

What is heteroblasty?

Answer 10

This refers to how some plants exhibit major differences between their juvenile and adult leaves.

Question 11

What is Heterophlly?

Answer 11

This refers to plants having leaves of different sizes/shapes (on the same plant).

Question 12

What is the difference between the phylloclade and the Cladode?

Answer 12

The are both flattened stems that take over leaf functions. However, Phylloclade is the modification of the entire stem and cladode is the modification of only a single internode of a stem.

Question 13

What is Phyllotaxy?

Answer 13

It is the pattern of organ initiation at the shoot apex or the arrangement of leaves on the stem.

Question 14

Shoot apical meristem vs. Shoot tip?

Answer 14

Both are a part of the shoot. The SAM is a region of the shoot tip which is where the primary growth of the shoot is concentrated.

Question 15

Node vs. Internode?

Answer 15

Node - the link regions between a leaf and stem.

Internode - the regions between two nodes.

Question 16

Central Zone vs. Peripheral Zone?

Answer 16

The central zone corresponds to the pro-meristem and shows infrequent division. It is surrounded by (like a ring) by the mitotically active Peripheral zone that gives rise to leaf primordia.

Question 17

What is the parenchyma?

Answer 17

Tissue present in all organs and is a ground tissue that generally constitutes the filler tissue in soft parts of the plants.

Question 18

What is the Collenchyma?

Answer 18

They provide structural support and are found adjacent to outer growing tissues such as vascular cambium.

Question 19

What is the Sclerenchyma?

Answer 19

Usually associated with the xylem and phloem of the vascular bundles. Bundles of sclerenchyma form durable layers such as the shell of nuts and seeds.