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Biology > structure , growth and devolopment of plants > Flashcards

structure , growth and devolopment of plants Flashcards

unit 4

1
Q

define a tissue

A

a tissue is a group of one or more cell types that carry out a specilized function .

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2
Q

what is a meristem

A

a meristem is undifferenciated tissues that are constently dividing under suitable condions to produce other new cells or new meristems .

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3
Q

what are the characteristics of meristems (6)

A
  1. living cells
    2.isodiametric
    3.has a dense cytoplasm
    4.has a central nucleus
    5.structurally and functionally undifferenciated
    6.has the ability to multiply
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4
Q

what are the 3 overlapping zones of cells consisting of succesive stages

A

cell divison
cell elongation
cell differenciated

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5
Q

what are the 3 types of meristems and explain the functions of the 3

A

apical , lateral , intercalary

1.apical - located at the root and shoot tips and they add new cells that increase the length of the plant .

2.lateral - it is located in the vascular and cork cambium . it increases the circumfarence of the root .the vascular cambium produces the secondary xylem and phloem and the cork cambium produces a thick and tough periderm to replace the epidermis .

3.intercalary - it is located in the base of stems and roots of monocots (grass) and involves in the rapid regrowth of the damaged leaves .

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6
Q

define the primery growth of the root

A

elognation of the root due to the activity of the primery meristems located in the root apex is called primery growth of the root

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7
Q

what are the 3 process that take place during the primery growth of the root and where do they take place

A

cell division - zone of cell division
cell elongation - zone of elongation
cell maturation - zone of differenciation

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8
Q

what type of cells do the zone of cell divison contain , what is its function , what is the function of the structure made .

A

the zone of cell divison contains root apical meristems and it s derivatives
it cuts cells to both sides and the cells cut downwards differenciate to form the root cap
the root cap will protect the root from the damage from friction when travelling through the soil .
the cells cut inwards go through cell elongation to more than 10 times the original .

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9
Q

define the primery growth of the shoot

A

the elongation of the shoot due to the activity of primery meristems located on the shoot apex called the primery growth of the shoot

unlike the root apex this only produce cells inwards

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10
Q

from what part of the shoot does the leaves devolop

A

leaf primodia

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11
Q

what are the changes that take place during the process of differenciation

A

changes in cytoplasm , cell wall and orgenelles

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12
Q

what are the 3 main tissue systems in vascular plants

A

vascular tissue system
dermal tissue system
ground tissue system

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13
Q

: What is the outer protective covering of plants?

A

The outer protective covering of plants is the epidermis.

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14
Q

Where is the epidermis found in plants?

A

The epidermis is found in the stems and roots of the primary plant body and leaves.

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15
Q

Describe the structure of the epidermis.

A

The epidermis is a tightly packed single-cell layer, normally covered by a cuticle in aerial parts.

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16
Q

what is the the cuticle

A

The cuticle is a waxy epidermal coating found on the aerial parts of the plant.

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17
Q

Name the specialized cells found in the epidermis.
what is the specialty in the guard cell ?

A

Specialized cells in the epidermis include:
- Guard cells - the only dermal tissue to contain a chloroplast
- Trichomes - epidermal outgrowths such as hairs and glands
- Root hair

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18
Q

list the functions of the epidermis
cutical -
root hair -
guard cells -
trichomes

4

A

Defense against physical damage and pathogens
- Cuticle prevents water loss
- Root hairs absorb water and mineral ions
- Guard cells facilitate gaseous exchange
- hair like trichomes reduce water loss and reflect excess light

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19
Q

What role do trichomes play in plant defense?

A

Some trichomes secrete chemicals that defend against insects , pathogens, and herbivores

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20
Q

What replaces the epidermis in older stems and roots after secondary growth?

A

A protective layer called the periderm

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21
Q

what are 2 types of ground tissue

A

pith - inside the vascular bundle
cortex - outside the vascular bundle

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22
Q

what are the functions of ground tissue cells

A

storage , photosynthesis , support and short distence transport

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23
Q

what are the 3 major types of cells present in the ground tissue system

A

parenchyma
collenchyma
sclerenchyma

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24
Q

true or false

1.parenchyma cells are living even at maturity
2.parenchyma cells have secondary cell walls most of the time
3.they have a large central nucleus

A

1.true
2.flase , they all have the primery cell wall which is thin flexible and most lack the secondary wall
3.false , they have a large central vacuole

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25
Q

explain the functions of the parenchyma cells

A

1.performs most of the metabolic activities in the plant - they synthesise various organic compounds

2.storage - some cells in the root and the stem contain plasmids(leucoplast ) which store more starch .

3.parenchyma cells often has the ability to divide and differenciate and has meristematic properties .this property helps it to restroe dammaged tissue and also helps in tissue culture practices .

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26
Q

compare the collenchyma cell with the parenchyma

A

the collenchyma is generally elongated and has a thicker primery cell wall than the parenchyma , the primery cell wall is unevenly thickened with cellulose .these cells are also flexible and they are living even in maturity

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27
Q

where is collechyma situated and what is it ‘s function

A

the young stems and petioles have collenchyma cells just below the epidermis .

function - the give mechanical support to leaves and stems without restraining growth .

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28
Q

how does the sclerenchyma tissue compare to other ground tissues

A

they are dead cells maturiy and the secondary cell wall is formed after cell elongation and i made up of lignin.

29
Q

what are the 2 types of sclerenchyma

A

sclereids and fibers

30
Q

compare and contrast the sclereids and fibers

A

sclereids - shorter and wider than fibers and has lignified secondary wall

fibers - grouped in strands , long slender and taperd

31
Q

what are the use or the fuctions of the 2 types of sclerenchyma

A

slcereids - they are found in places where growth has already stopped .
eg- nut shells , shell of coarse fruits , seed coats

fibers - used to commercially obtain fibers
coconut husk fiber and hemp fiber

32
Q

what are the 2 types of tissue in vascular tissue

A

xylem and phloem

33
Q

what are the types of cells in xylem and which of them are living

A

xylem vessel element
xylem parenchyma - living
tracheids
xylem fiber

34
Q

the only gymnosperm to contain xylem vessel element is

A

Gentophyta phylum

35
Q

what are the functions of all the cells in the xylem

A

xylem vessel element - water transport and provide support to prevent collapse under the tension of the water transport .
tracheids - water transport
fibers - give mechanical support
xylem parenchyma - storage and radial transport

36
Q

what are the features of the xylem vessel element

A

long , cylindical
dead cells
the secondary walls are thickend by lignin
perforation plates are present at eh end walls of the vessel element . other walls are interupted by pits

37
Q

what are the features of tracheids

A

long thin cells with tapering ends
the secondary cell wall is thickend by lignin - this provide support not to collapse under the pressue . and is interupted by pits.
and they are also found in all vascular plants unlike vessel element which is in all angiospersm and some gymnosperms .

38
Q

what are the cell types in the pholem tissue and which of them are living

A

seive tube element - living
pholem parenchyma - living
companion cells - living
phloem fibers

39
Q

What type of phloem cells are present in seedless vascular plants and gymnosperms instead of sieve tube elements?

A

In seedless vascular plants and gymnosperms sieve tube elements and companion cells are absent. Instead of sieve tube elements, long narrow cells called sieve cells are present in these plants.

40
Q

What cellular components are absent in sieve tube elements?

A

Sieve tube elements lack a nucleus, ribosomes, a distinct vacuole, and cytoskeletal elements.

41
Q

What happens to the cytoplasm in sieve tube elements?

A

The cytoplasm in sieve tube elements is reduced to a thin peripheral layer.

42
Q

Why do sieve tube elements lack certain cellular components?

A

The absence of components like a nucleus and ribosomes allows nutrients to pass more freely through the sieve tube elements.

43
Q

How are sieve tube elements arranged in phloem?

A

Chains of sieve tube elements are aligned to form sieve tubes.

44
Q

What is the function of the sieve plate in sieve tube elements?

A

The sieve plate, found on the end walls between sieve tube elements, allows fluid to move from one sieve element to the next.

45
Q

What are non-conducting cells in the phloem, and where are they found?

A

Non-conducting cells are found alongside each sieve tube element and are connected to the sieve tube element by numerous plasmodesmata.

46
Q

What is the role of the nucleus and ribosomes in non-conducting cells?

A

The nucleus and ribosomes of non-conducting cells also serve the adjacent sieve tube element, supporting its functions.

47
Q

How do some companion cells aid in phloem transport?

A

in leaves help in phloem loading, while in other organs, they assist in phloem unloading.

48
Q

what is defined as growth

A

the irreversible increase of dry mass of an organism

49
Q

what are the diffrent types of parenchyma

A

pericycle and endodermis

50
Q

what is the ground tissue between the vascular bundle and the epidermis called ? what is it made up of

A

cortex , parenchyma cells with intercellular spaces

51
Q

what are the functions of the cortex

A

storing carbohydrates , and transports water and minerals towards the endodermis

52
Q

what is the endodermis defined as and what is it made up of ?

A

the innermost single cell layer of the cortex , parenchyma

53
Q

what blocks the vascular appoplast from the cortical appoplast

A

the belt called the casparian strip in the endodermis

54
Q

what is the casparian strip made up of , what is it’s bio molecule type

A

suberin , it is a lipid (Wax)

55
Q

what is the exact location of the pericycle

A

the 2 or 3 cell layers of parenchyma which are interior to the endodermis

56
Q

explain the pericycle in the dicto root

the location and the function (2)

A

the pericycle parenchyma cells have meristamatic abilities

it involves in the growth of the lateral roots and the secondary root

57
Q

explain the pericycle in the monocot root ?

A

they do not have meristamatic abilites

58
Q

what is the arrangemnt of the vascular bundel in the monocot root

A

it is in a ring of alternating xylem and pholem

59
Q

what is the function of the epidermis in the dicto stem

A

to prevent from dessication and infections

60
Q

what interupts the epidermis in the dictot stem

A

pores called stomata

61
Q

what is the function and the location of collencyma and sclerenchyma cells in the dicot root

A

near the vascular bundle and right below the epdermis

62
Q

what is the arrangment of the vascular budle in the dicto stem

A

it is arranged as a ring and it grows the primery xylem towards the pith and the primery pholem towards the cortex

63
Q

what is outside the dicto stem vascular bundle

A

cluster of sclerenchyma

64
Q

what structure contains the large luman

A

dicot stem - has a large pith

65
Q

from where are the lateral roots born

A

auxiliary bud

66
Q

Is the ground tissue of a monocot shoot differentiated into cortex and pith?

A

no they are noT differencuate into cortex and pith

67
Q

What surrounds each vascular bundle in a monocot stem?

A

A: Each vascular bundle is surrounded by sclerenchyma.

68
Q

what is the speciality in the vascular bundle int he monocot stem

A

it does not have a cambium in the middle of the xyleme and the phloem

69
Q

what is the arrangment of the vascular bundles in the monoco stem

A

it is scatterd thorougt the ground tissue

Biology (9 decks)

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