Cell Communities

Question 1

Name the three different types of land plants.

Answer 1

1. Avascular (Bryophytes) - Mosses, liverworts and hornworts.
2. Vascular (but seedless) - Ferns, clubmosses and horsetails.
3. Seed plants - Angiosperms and gymnosperms.

Question 2

State five common features of a plant.

Answer 2

1. Multicellular.
2. Apical meristems.
3. Cell wall is used for support and rigidity.
4. They have specialised reproductive organs.
5. Spores or seeds with specialised walls which stop them from drying out.

Question 3

State three features of apical meristems.

Answer 3

1. Localised regions of dividing cells.
2. Result in primary growth (length).
3. Produces three primary meristems which develop into three tissue types.

Question 4

What class of growth does lateral meristems result in?

Answer 4

Secondary (girth).

Question 5

Define dermal tissue.

Answer 5

Outer protective covering.

Question 6

Define vascular tissue.

Answer 6

Root and shoot transport.

Question 7

Define ground tissue.

Answer 7

Any tissue that isn’t dermal or vascular.

Question 8

What are the three basic plant organs?

Answer 8

1. Roots.
2. Stem.
3. Leaves.

Question 9

Describe the structure of leaves.

Answer 9

It has variable morphology, comprising flat blade and petiole (leaf stalk). It contains veins (vascular tissue) which is parallel in monocots and is a network in dictos.

Question 10

Describe the function of leaves.

Answer 10

It is the main photosynthetic organ. It also provides support, protection, storage and reproduction.

Question 11

What is the dermal tissue of a root, stem and leaf?

Answer 11

Epidermis.

Question 12

What are the two ground tissues of a root, stem and leaf?

Answer 12

1. Cortex and pith.

2. Mesophyll.

Question 13

What are the three vascular tissues of a root, stem and leaf?

Answer 13

1. Phloem.
2. Xylem.
3. Vascular bundles.

Question 14

Describe the structure of stems.

Answer 14

It has alternating nodes (leaf attachment points) and internodes.

Question 15

Describe the function of stems.

Answer 15

1. To support leaves, flower and fruit.
2. To transport between root and shoot.
3. Activity at apex leads to primary growth.
4. Storage of nutrients.
5. Some photosynthesis.
6. Asexual reproduction (stolons).

Question 16

Describe the structure of roots.

Answer 16

Dicots - main taproot and lateral roots.

Monocots - mass of fibrous roots.

Question 17

Describe the functions of roots.

Answer 17

1. Anchors plants in soil. Prop and buttress roots improve support.
2. Absorbs minerals and water.
3. Stores carbohydrates.

Question 18

What are the four functions of the epidermis?

Answer 18

1. Protection against damage and pathogen.
2. Reflects excess solar radiation.
3. Cuticle reduces water loss.
4. Defence against insect herbivory.

Question 19

Define periderm.

Answer 19

Replaces epidermis in old stem/root regions of woody plants.

Question 20

What three layers form in early secondary growth?

Answer 20

1. Cork cambium.
2. Cork cells deposit suberin in walls then die.
3. Phelloderm which is the inner layer of living parenchyma.

Question 21

Define xylem.

Answer 21

Water conducting tissue.

Question 22

State four features of tracheary elements (TE).

Answer 22

1. Dead at maturity.
2. Elongated with lignified walls.
3. Linked by pits/perforation plates.
4. Its main role is to conduct water and minerals.

Question 23

What does fibres and lignified tracheary element provide?

Answer 23

Support.

Question 24

What does xylem parenchyma provide?

Answer 24

A storage role and living cells.

Question 25

Define tracheary elements.

Answer 25

Xylem elements without plates in angiosperms only.

Question 26

Define phloem.

Answer 26

Photosynthate conducting tissue.

Question 27

State five features of conducting cells.

Answer 27

1. Long, narrow sieve cells (gymnosperms). 2. Linked sieve tube members (angiosperms). 3. They are living cells with reduced contents. 4. The nucleus and ribosomes of companion cell serve both cells. 5. Perforated sieve plates link cells.

Question 28

In roots and stems, what is the ground tissue internal to vascular tissue known as?

Answer 28

Pith.

Question 29

In roots and stems, what is the ground tissue external to vascular tissue known as?

Answer 29

Cortex.

Question 30

What two types of tissue are ground tissue in leaves?

Answer 30

1. Spongy mesophyll. | 2. Palisade mesopyhll.

Question 31

State four features of parenchyma.

Answer 31

1. Thin, flexible walls as there is no secondary wall. 2. Large central vacuole. 3. Contain plastids. 4. Ability to divide and differentiate.

Question 32

In what four places are parenchyma found?

Answer 32

1. Cortex and pith of stem. 2. Mesophyll of leaves. 3. Flesh of fruits. 4. Reproductive structures.

Question 33

What four metabolic functions does parenchyma carry out?

Answer 33

1. Photosynthesis in mesophyll. 2. Storage e.g. amyloplasts store starch. 3. Regeneration/wound healing (meristematic). 4. Support e.g. in stems.

Question 34

State a feature of collenchyma.

Answer 34

Thick primary walls with no lignin, this it is soft and stretchy.

Question 35

State a function of collenchyma.

Answer 35

Flexible support for growing tissues.

Question 36

What two places are collenchyma found?

Answer 36

1. Stems, petioles and young organs. | 2. As elongated strands or cylinders beneath epidermis.

Question 37

State two features of sclerenchyma.

Answer 37

1. Thick, lignified secondary walls. | 2. May be dead at maturity.

Question 38

State a function of sclerenchyma.

Answer 38

It supports non-growing plant parts.

Question 39

What are the two types of sclerenchyma?

Answer 39

1. Fibres - Long, thin cells in bundles. | 2. Sclereids - Short, irregular shape.

Question 40

What two places are sclerenchyma found?

Answer 40

1. Fibres in stems. | 2. Sclereids in seed coats and pear flesh.

Question 41

State four functions of cell walls.

Answer 41

1. Cell protection. 2. Maintains cell shape. 3. Holds plant up against gravity. 4. Avoids excess water uptake.

Question 42

What is a secondary cell wall composed of and what does this mean for its structure?

Answer 42

It is composed of cellulose and lignin. This makes the wall rigid.

Question 43

What is the structure of a primary cell wall like?

Answer 43

It is thin, flexible and mainly composed of cellulose.

Question 44

Define middle lamellae.

Answer 44

Adhesive pectins between cells.

Question 45

Define gap junctions.

Answer 45

Cytoplasmic channels between cells in animal tissues.

Question 46

State two features of plasmodesmata.

Answer 46

1. They perforate the cell wall. | 2. They encompass a cytoplasmic sleeve, desmotubule (SER) and cell membrane.

Question 47

What is the purpose of cell junctions?

Answer 47

They allow exchange of ions, proteins, mRNA and virus DNA.

Question 48

State three reasons why plant roots anchor plants to one spot.

Answer 48

1. They must defend themselves against herbivory. 2. They must deter competitors. 3. They must attract pollinators.

Question 49

Define metabolites.

Answer 49

Intermediates/products of metabolism.

Question 50

Define secondary metabolites.

Answer 50

They deter herbivores.

Question 51

Define determinate growth. What type of cell does this happen to?

Answer 51

Growth stops at a certain size. This happens to animal cells.

Question 52

Define indeterminate growth. What type of cell does this happen to?

Answer 52

Growth throughout life. This happens to plant cells.

Question 53

Explain two reasons why indeterminate growth acts as plant defence.

Answer 53

1. Possible due to meristems: - Mitotically active regions. - Produce new undifferentiated tissue. 2. Allows recovery from damage.