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HORT 1102 - Botany > 6: Primary Growth & Root Symbiosis > Flashcards

6: Primary Growth & Root Symbiosis Flashcards

1
Q

What are the 3 distinct organelles of plant cells?

A
  • Chloroplast: absorb sunlight and convert into sugar
  • Cell wall: not living, provides structure and strength to cells
  • Vacuole: contains 98% water and occupies a large portion of a cell
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2
Q

What happens to the cell membrane when the vacuole has positive pressure (is filled with water)?

A

The vacuole will push against the membrane which will push against the cell wall and the cell becomes TURGID or sturdy

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3
Q

Describe passive diffusion

A

the selectively permeable cell membrane will allow some dissolved substances to move through without energy required as they move with the concentration gradient

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4
Q

Describe active transport

A

energy (ATP) is required for substances to move through the membrane

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5
Q

What is the plasmodesmata?

A

Allows the flow of water and material between cells

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6
Q

What are the two kinds of cell walls? What are they each made up of?

A
  1. Primary Cell Wall: made up of CELLULOSE

2. Secondary Cell Wall: made up of SUBERIN & LIGNIN

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7
Q

What is cellulose?

A

the composition of the primary cell walls in plant cells that make the cells flexible

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8
Q

What is suberin?

A

a waterproof compound found in tissues of tree bark and roots

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9
Q

What is lignin?

A

a very tough compound that makes cells strong

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10
Q

What is lamella?

A

a glue that holds together the primary and secondary cell walls. Where pectin is found

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11
Q

What are the 3 cell types?

A
  1. Parenchyma
  2. Collenchyma
  3. Sclerenchyma
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12
Q

What are the 3 key points for parenchyma cells? Where are they found? What is their role?

A

Key points:

  1. thin walled cells with soft, flexible cell well - not strong
  2. Divide easily by mitosis
  3. Alive at maturity

Location:
in the epidermis and pith

Role:
fill space, store starch, contain chloroplasts

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13
Q

What are the 3 key points for collenchyma cells? Where are they found? What is their role?

A

Key points:

  1. Alive at maturity
  2. Contain thickened primary cell walls for strength
  3. Cells provide structure for leaf veins

Location:
- young dicot stems and midrib of leaves

Role:
- to provide strong, but flexible/elastic structure to midrib of leaves

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14
Q

What are the 3 key points for sclerenchyma cells? Where are they found? What is their role?

A

Key points:

  1. Dead at maturity
  2. Extra thick secondary cell walls containing lignin
  3. add strength and toughness
  4. fibre cells

Location:
- herbaceous and woody stems

Role:
provide strength and structure in woody stems

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15
Q

What are sclereids? Where are they found?

A

Key points:

  • make the pit or endocarp of a stone fruit hard
  • the gritty texture of pears
  • boxy structure
  • dead at maturity
  • very thickened secondary cell walls filled with lignin
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16
Q

What are the roles of root systems?

A
  • anchor plants to establish contact with the ground
  • ABSORB WATER & NUTRIENTS
  • Transport water & nutrients to the shoot
  • store carbs in the form of starch
  • synthesize hormones
  • can be a site for secondary compound production to protect plant tissues from pests/disease
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17
Q

What are the 3 root system types?

A
  1. Tap root system
  2. Fibrous root system
  3. Storage & Tuberous roots
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18
Q

Describe tap root systems

A

the primary root starts as a tap root and lateral roots will increase surface area underground

19
Q

Describe fibrous root systems

A

the primary root is taken over by lateral roots creating a fibrous system OR
adventitious roots form from the stems or leaves to create a fibrous system

20
Q

Describe aerial roots

A

Roots that grow above ground

21
Q

What are the 5 kinds of roots?

A
  1. Fibrous roots
    - ex. grass
  2. Adventitious roots
    - corn
  3. aerial roots
    - tropical plants
  4. Storage tap roots
    - carrots
  5. fleshy fibrous roots
    - ex. spider plants
  6. tuberous roots
    - ex. dahlias
22
Q

What is primary root growth?

A

the growth that occurs i the first year

23
Q

Describe the root cap

A
  • Parenchyma cells cover the apical meristem
  • secretes mucigel
  • cells live less than 1 week
  • site for perception of gravity (downwards growth)
24
Q

What are the 3 regions of a root tip?

A
  1. Region of cell division
  2. Region of elongation
  3. Region of maturation
25
Q

What occurs in the region of cell division in the root tip?

A
  1. Mitosis takes place every 12-35 hours
  2. new cells are shaped like cubes and closely packed
  3. the new cells subdivide into 3 meristematic groups
26
Q

What occurs in the region of elongation in the root tip?

A
  • located within 1cm of the tip of the root
    1. cells extend several times in length
    2. smaller vacuoles within cells merge into one large vacuole (to take up to 90% of space)
27
Q

What occurs in the region of maturation in the root tip?

A
  1. elongation ceases

2. cells mature to their final form

28
Q

Describe root hairs

A

tubular extensions of specialized epidermal cells that increase the absorptive surface area of the root system

they only live a few days and are constantly renewed by the growing root tip

29
Q

What are the 8 tissues with a dicot root?

A
  1. Epidermis
  2. Cortex & Endodermis
  3. Pericycle
  4. Phloem
  5. Xylem
  6. Cambium
30
Q

Describe the cortex tissue of a dicot root?

A

Composed of primarily parenchyma cells that store starch.

The inner layer of the cortex is called the endodermis

31
Q

Describe the epidermis

A

The outer layer of cells that cover the outside of the root

32
Q

Describe the endodermis

A

The inner layer of the cortex that contains primary xylem and phloem tissue. It also has the Casparian Strip which contains suberin to make portions of the endodermis waterproof. Some of the endodermis is made up of PASSAGE CELLS which do not contain suberin and allow substances to flow through.

33
Q

Describe Casparian strip

A

Found in the endodermis layer

A waxy (suberin) deposit in the cell walls of the endodermal cells force water to move through the interior of the cell to filter out unwanted chemicals or spores

34
Q

Describe pericycle

A

found in dicot roots

Composed of parenchyma cells which can divide by mitosis if required

the pericycle cells at the end of a xylem “arm” divide by mitosis to produce a root initial that will develop into a lateral root

35
Q

Describe lateral root development

A

found in dicot roots

the lateral root will develop its own apical meristem and push outward as more cells are added
eventually it will break through the endodermis, cortex, and epidermis as the root extends

36
Q

Describe xylem tissue

A

Big pipes (vessel and tracheid cells) that carry water and nutrients up to the shoot

37
Q

Describe phloem tissue

A

Living cells that carry dissolved sugars down the shoots to where they are needed

38
Q

Describe pro-cambium

A

found in dicot roots

forms between the xylem and phloem tissue.
the cells divide and produce secondary growth (growth ring)

39
Q

What tissues do monocot roots have?

A
  1. Epidermis
  2. Endodermis & Casparian Strip & Passage Cells
    3: Pericycle
  3. Cortex
  4. Pith
  5. Xylem
  6. Phloem
40
Q

Describe root nodules. Give an example

A

Occur when bacteria invade cortical (cortex) cells of certain plants to make a home
ex. It is usually a symbiotic relationship like the one between nitrogen-fixing bacteria and roots

41
Q

Describe ECTO-Mycorrhizae

A

Fungi connect to the root tip to find a “home” to IMPROVE the health of the root and share nutrients and sometimes water with the root as part of the exchange for a home

42
Q

Describe the apical bud and what is its function?

A

aka the terminal bud

Where new vertical growth occurs
- all new cells are produced i the apical meristem

  • cells will expand in size and mature into any type of cell
  • they are grouped, depending on location, into meristems which produce more cells that mature into tissues with specific functions
43
Q

T or F: Monocot stems & roots will develop a pro-cambium between the xylem and phloem

A

FALSE. A pro-cambium will not develop

HORT 1102 - Botany (11 decks)

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