18 - Plant Form & Internal Architecture

Question 1

List some root/shoot minimalisation features and examples of them.

Answer 1

Minimal roots e.g. bromeliads, mistletoe.
Minimal shoots e.g. dendrophalax.
Minimal roots and shoots e.g. tristerix, rafflesia.

Question 2

List the 6 main differences between monocots and eudicots.

Answer 2

Monocots: one cotyledon, parallel leaf venation, arranged stems, fibrous roots, petals in multiples of 3.
Eudicots: two cotyledons, netlike veins, stem arranged in ring, taproot, petals in multiples of 4/5.

Question 3

Describe the ground plan of flowering plants.

Answer 3

An apical growth centre (meristem) produces the main stem. At intervals along the stem, axillary buds are produced which generate a branch stem or a flower. Each axillary bud rises above a leaf.

Question 4

List some stem variations (physical characteristics).

Answer 4

Longitudinal spacing, circumferential distribution, orientation of growth, apical dominance.

Question 5

What is vascular and cork cambium? Only present in eudicots.

Answer 5

Vascular cambium – forms a ring to the vascular tissue.

Cork cambium – bits of tissue that form the core of the growth of the plant.

Question 6

Why can’t monocots increase their stem diameter?

Answer 6

They have reduced mechanical support that restricts them. Prop roots have arisen to provide support.

Question 7

What are some foliage/leaf variations?

Answer 7

Longitudinal spacing, phylotaxis e.g. alternate and whorled, compound leaves, spines.

Question 8

List some root modifications.

Answer 8

Root vegetables e.g. carrots, prop roots, storage roots, strangling aerial roots, buttress roots, pneumatophores.

Question 9

What are the 3 tissue systems?

Answer 9

1. Dermal: Epidermis, periderm.
2. Vascular: xylem, phloem.
3. Ground: paren-, scleren-, collenchyma.

Question 10

List different plant cells and their function.

Answer 10

Parenchyma: metabolism.
Collenchyma/Sclerenchyma: support. 
Epidermal: protection and environment exchange.
Phloem/xylem: transport.
Meristematic cells: generative.

Question 11

What is the difference between primary and secondary growth?

Answer 11

Primary: increases length and girth, maturation of cells of apical origin.
Secondary: increases girth, maturation of cells of non-apical origin, produces woody stems. (not for monocots)

Question 12

How does vascular cambium work/form?

Answer 12

1. Formation of first cambium cells.
2. Initial cells divide to generate xylem and phloem or other cambium cells.
3. The cells keep dividing to form the secondary xylem and phloem as well as the woody stem.

Question 13

What do rings in wood mean?

Answer 13

They reveal age. The larger the diameter the older the tree. They form when the xylem vessels are small and the bark is pushed out.

Question 14

Describe the structure of eudicot roots.

Answer 14

Radial structure. Vascular tissue lies in central stele, which consists of the endodermis, pericycle, xylem and phloem.

Question 15

What are Mycorrihizal associations?

Answer 15

Plant associates with a fungus. Fungi receives sugars and carbs while plant receives water from them.