Plant Organs

Question 1

Name 6 important functions of stems

Answer 1

• mechanical support
• bear leaves - photosynthesis
• flowers - pollination
• distribution of fruit
• transport of water & dissolved salts
• distribute organic food

Question 2

what is primary growing

Answer 2

stems grow longer in the apical growing tips of stems

Question 3

what is secondary growth

&

where does it occur

Answer 3

• becomes thicker
• develop more tissues for:
  • strengthening & support
  • transport & metabolic activity
• occurs in the cambium

Question 4

what are lenticles

Answer 4

small wart-like spots
young stems of perennial plants ( trees)
GASEOUS EXCHANGE

Question 5

medulla & medulla rays

Answer 5

• found between vascular bundles
• mainly consist of parenchyma
• stores food
• forms ventilation tissue in some plants

Question 6

central cylinder

Answer 6

• contains vascular tissue

Question 7

what is the layer of cambium between xylem and phloem known as

Answer 7

vascular or fascicular cambium

Question 8

explain the sclerenchyma in/around the vascular bundles

Answer 8

• sclerenchyma on outside for protection

* occurs in strands : sclerenchyma cap / pericycle cap

Question 9

Describe in full the epidermis

Answer 9

• covered in a waxy cuticle

* differentiate into guard cells, stomata, trichomes

Question 10

Name the functions of the epidermis

Answer 10

• protects underlying layers
• prevents excessive loss of water through evaporation
• allows gaseous exchange for respiration & photosynthesis

Question 11

what is the inner layer of the cortex called

Answer 11

starch sheath

Question 12

what is the function of the cortex

Answer 12

produces food ( young ) 
stores food ( older )

Question 13

what 2 ground tissues protect and strengthen the stem

Answer 13

• collenchyma

* sclerenchyma

Question 14

why do dicot stems have “open” vascular bundles

Answer 14

• it had cambium

* secondary growth can take place

Question 15

explain in full detail the specific pattern of secondary growth

Answer 15

• parenchyma in medulla rays become secondarily meristemic & form strip of cambium -> INTERFASCICULAR CAMBIUM
• fascicular & interfascicular form CAMBIUM RING
• cambium ring now forms secondary xylem on inside & secondary phloem on outside
• OG xylem & phloem are pushed outta the way and later found part of medulla & bark
• xylem cylinder becomes thicker & cambium ring becomes wider & phloem ring also wider

Question 16

what can the annual rings tell us about the plant?

Answer 16

• the age of the tree

* the weather

Question 17

describe the development of bark

Answer 17

1. cork cambium develops below the epidermis of stem when parenchyma cells of cortex become secondarily meristematic
2. cork cambium produces cork cells to the outside

Question 18

what is cork cambium impregnated with

Answer 18

suberin

Question 19

what are the functions of cork

Answer 19

• waterproof
• protect against water loss
• protect against mechanical injury

Question 20

name 6 xylem characteristics that aid in supporting & strengthening plants

Answer 20

• thickened cell walls
• strengthened by lignin
• cellulose fibres in cell walls arranged in a way that lends support & elasticity
• rounded in cross section
• strengthened by thickenings
• xylem is a solid cylinder
• xylem has a degree of elasticity

Question 21

name 4 reasons why water is important for plants

Answer 21

• large plant body consists of water
• water is universal solvent
• important for transport of substances
• takes part in chemical reactions -> photosynthesis

Question 22

what’s transpiration

Answer 22

water evaporates from aerial parts of the plant

Question 23

how does the stomata open & close

Answer 23

• mainly based of the water potential of the guard cells
• guard cells turgid: pore open
• guard cells flaccid: result of exosmosis pore closes

Question 24

what are the 3 types of transpiration

Answer 24

• stomatal transpiration
- evap from intercellular air spaces thro stomata

• cuticular transpiration
- evap ( v small amount ) from epidermal cells through cuticle

• lenticular transpiration
- evap ( small amount ) from air spaces by means of lenticle

Question 25

what is guttation and when does it happen ( conditions ) and how does it work

Answer 25

loss of water in liquid form from the leaves on a plant during night when environmental temp is high & soil moist water forced through openings the hydatodes

Question 26

name 3 environmental factors that influence rate of transpiration

Answer 26

* light intensity ( stomata usually open during the day ) - evap increase * environmental temperature is high - evap increase * wind ; blows over aerial parts keeping water potential of surrounding air low - evap faster

Question 27

COMPARISON TABLE BETWEEN GUTTATION & TRANSPIRATION

Answer 27

117

Question 28

how is the leaf adapted for the process of photosynthesis

Answer 28

* leaf is flattened to offer large surface area * leaf is thin * epidermal cells are transparent * vascular bundles form network through the leaf * stomata on leaves - gaseous exchange * palisade parenchyma ; chloroplasts, elongated, densely packed * spongy parenchyma loosely packed -> gaseous exchange

Question 29

what are the 2 types of root systems? describe where they are found

Answer 29

* tap root system : found in dicots & gymnosperms | * adventitious root system: found in monocots

Question 30

Describe the 3 different types of roots

Answer 30

tap: embryonic radicle that grows and develops ( primary root ) adventitious: any root that grows from any other plant organ except from another root lateral root: develops from another root; branch ( secondary root )

Question 31

name 5 external regions that can be identified in a mature root

Answer 31

* apical meristem * root cap * area of elongation * root hair region * permanent region

Question 32

name 3 things the pericycle can form into | and not

Answer 32

* lateral roots * vascular cambium * cork cambium in roots don’t undergo secondary thickening; pericycle turned into sclerenchyma

Question 33

how can we identify xylem in a young root

Answer 33

cross or 5 pointed star

Question 34

what is the endodermis?

Answer 34

later of cells that controls the passage of water to the center cylinder

Question 35

what are casperian bands

Answer 35

* rings made of suberin | * direct the movement of water from cortex to central cylinder

Question 36

name 2 dermal tissues that protect and cover the plant

Answer 36

* epidermis | * periderm

Question 37

what is the difference between herbaceous stems and woody stems

Answer 37

herbaceous: covered by one layer of epidermis cells woody: have the same but then tears and replaced by the periderm which forms part of the bark

Question 38

describe the cells of the epidermis

Answer 38

* brick shaped * variety of shapes * don’t contain chloroplasts & transparent * guard cells have chloroplasts * covered in waxy layer called cuticle * trichomes