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Rhs r2101 > R2101 > Flashcards

R2101 Flashcards

1
Q

State the function of a stem

A

The primary function of a stem is to provide structural stability, to support the leaves flowers and fruits and to transport water and nutrients between roots and leaves.

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2
Q

Describe the external structure of the stem

A 
External structures
Node
Internode
Axillary bud
Axil
Apical bud
Leaf and scale scars
Lencitels
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3
Q

Describe the internal structure of the stem

A

Epidermis
cortex
Vascular bundle consisting of xylem, phloem and cambium
Pith

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4
Q

What is the function of a node

A

A node is an area on a stem where buds, leaves and branching twigs originate. The node is a site of great cellular activity and growth. The primary function of a node is to support the plant holding the leaves flowers and buds

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5
Q

What is the function of an internode

A

Internodes are the part of the stem between two nodes. It provides support for the leaf flower and fruit and carries water food and hormones from node to node.

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6
Q

State the function of the axillary bud

A

The axillary bud or lateral bud is the embryonic shoot located in the axil of a leaf. each bud may form shoots and may be specialized l to form vegetative or reproductive shoots.

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7
Q

State the function of the leaf axil

A

The leaf axil is the point on the main stem where buds or shoots develop. The axil can be a useful guideline for growth and pruning

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8
Q

State the function of the apical bud

A

The apical bud or terminal bud is the primary growing point at the apex of the stem. The apical bud produces auxin which inhibits growth of lateral buds.

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9
Q

State the function of lenticels

A

Lenticels are found on woody stems, they are raised circular areas which facilitate the gas exchange of oxygen, carbon dioxide and water vapor from the outer atmosphere to the inner tissues of the stem.

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10
Q

State the function of a leaf scar

A

A leaf scar is mark left after a leaf falls from the twig and marks the spot where the petiole was once attached to the stem. The leaf scar can be a useful tool to identify plant species during winter

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11
Q

State the function of a Scale scar

A

Scale scars are scars remaining after the bud scales fall off. The age of the stem can be determined from these scars

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12
Q

Describe the internal structure of a stem

A

The stem is composed of three tissue systems that include the epidermis, vascular, and ground tissues, all of which are made from the simple cell types..

The epidermis is a single layer of cells which make up the dermal tissue which covers the stem and protects the underlying tissue

The vascular tissue consists of xylem and phloem which carry water and nutrients up and down the length of the stem and are arranged in distinct strands called vascular bundles.

The ground tissue helps to support the stem and is called pith when it is located towards the middle of the stem and called cortex when it is located between the vascular tissue and the epidermis.

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13
Q

Describe how the stem is adapted to perform other functions

A

Stems often adapt to aid the plant in reproduction and to better regulate and distribute water and nutrients

Thorns and prickles provide protection for plants such as rosa and crataegus

Storage or perennation stems allow plants to survive in unfavorable conditions. Crocus have adapted corms and iris have developed rhizomes

Climbing Plants like wisteria have developed twining stems which wind around other plants or uprights for support, other plants have developed tendrils to help them to climb.

Other stem adaptation allow for natural vegetative reproduction.
Stolons/runners : FRAGARIA
Rhizomes : IRIS
Stem tubers: SOLANUM TUBEROSUM

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14
Q

State the primary function of leaves

A

produce food by the process of photosynthesis

-release excess water by the process of transpiration

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15
Q

Describe the structure of a leaf

A

Petiole
Lamina
Veins
Midrib

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16
Q

What is the function of a petiole

A

the stalk attatching the leaf to the stem

. It provides flexibility in positioning for the leaf to gain maximum light

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17
Q

What is the leaf Lamina

A

The lamina is the whole leaf/blade.
It is a flat and usually thin region of the leaf which contains chloroplasts and stomata which s crucial for photosynthesis and gaseous exchange

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18
Q

what is the midrib

A

The midrib is the main vascular bundle of the leaf that runs along the center of the lamina and provides strength throughout the leaf

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19
Q

What are leaf veins

A

A web of vascular tissue that spreads from the midrib, providing transportation of water and nutrients between the leaf and the stem.

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20
Q

Describe how leaves are adapted to form other function

A

A leaf adaptation for perennation and food storage which allows the bulb to survive from season to season. (lillium/ narcissus)

The leaves of sedums allow plants to survive hot desert environments by storing water in its leaves
The leaf spine of berberis serves to protect the plant from predators whilst hydrangeas produce bracts to attract and encourage pollinators

Tendrils on Lathyrus and twining petioles of clematis offer support for the plant as it climbs up structures

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21
Q

State the function of flowers

A

Flowers are organs of sexual reproduction which give rise to seeds and fruits. In order to reproduce they must attract beneficial insects to aid in pollination.

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22
Q

Draw vertical section of a monocot and a dicot flower

A 
Receptacle
tepal
sepal
petal
calyx
corolla
nectary
anther
filament
stamen
stigma
style
ovary
ovule
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23
Q

State the meaning of monoecious in relation to plants and give two plant example

A

Monoecious plants have both male and female organs on separate flowers of the same plant.
Quercus robur
Betula

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24
Q

State the meaning of dioecious in relation to plants and give two plant examples

A

Dioecious plants have male and female organs on different plants plants
Ginkgo
Salix

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25
Q

State the meaning of the term pollination

A

the transfer of pollen from the anther of a male flower to the stigma of a female flower to allow fertilization.

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26
Q

Describe the characteristics of bee/insect pollinated plants

A

Plants that are pollinated by insects tend to have large showy flowers, scent or secretion of nectar to attract the insect.
Pollen is transferred by the body of the insect coming into contact with the anther and stigma and the pollen brushing off.

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27
Q

Describe the characteristics of wind pollinated plants

A

Insignificant flowers with anthers and stigma exposed
They produce large quantities of pollen to increase the chance of it hitting an appropriate stigma. The pollen grains are very small so they can be carried long distances in the wind.

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28
Q

State the meaning of the term fertilisation

A

Plant fertilization is the union of male and female gametes (reproductive cells) to produce a zygote (fertilized egg).

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29
Q

State the meaning of the term fruit

A

a fruit is the seed-bearing structure in flowering plants. They are a result of fertilisation and are formed from the ovary after flowering. The purpose of the fruit is to provide protection for the seed.

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30
Q

State the meaning of the term seed

A

Seeds are formed from the female ovules as a result of fertilisation and are the prime method by which flowering plants reproduce.

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31
Q

State the function of fruits

A

The fruits of a plant provide protection for seeds and It attracts animals that help in dispersing or scattering the seeds to distant places.

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32
Q

State the function of seeds

A

Seeds are the reproductive structure which contain a plant embryo, the seed is capable of protecting the embryo and providing it with a source of food. Seeds are dispersed/transported to new a new site for germination and the establishment of new plants
Seeds can impose dormancy which prevents seeds from germination in unsuitable conditions which would likely lead to a low probability of seedling survival

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33
Q

Describe how seeds are dispersed

A

Seed dispersal is the movement, spread or transport of seeds away from the parent plant to form new plants. There are many ways in which seeds can be dispersed.

Wind: PAPAPVER/ ACER
Some seeds are very small and are easily carried by wind and some have devices which assist them in the wind. (Winged/parachute/ censer)

Animals: MICE / BIRDS/ SQUIRELS
some seeds are sticky or have burrs which cause them to stick to the coats of animals (attatchment) or are eaten by animals which are subsequently excreted (frugivory) Many animals gather seed and scatter them in multiple locations burrying them in the ground to return to at a later date. (scatter hoarding)

Explosive: CARDAMINE HIRSUTE/ HIMALAYAN BALSAM
Some plants eject their seed in reaction to being touched

Water : HIMALAYAN BALSAM
Few seeds are dispersed by water but those that do have lightweight seeds that are able to float on the water surface until they reach land where they can germinate

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34
Q

Describe the internal and external structure of a seed and describe function of its components

A

External:
Testa : Seed coat which protects the seed

Hilum : Scar left from the seed where it was previously attatched to the wall of the ovary

Micropyle: Small hole in the testa where the pollen tube entered the ovule at the time of fertilisation.

Internal:
Cotyledon: First Seed leaf/leaves providing a food store for the germinating seed

Plumule: part of the seed which forms the first shoot

Epicotyl: Connects the cotyledon to the plumule

Hypocotyl: Connects the cotyledon to the radicle

Radicle: Part of the seed which forms the first root

Endosperm: The endosperm is not present in all seeds. it is formed during fertilisation and is used as a food source for the embryo as it grows to form the seed

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35
Q

Describe the difference between epigeal and hypogeal germination

A

epigeal germination takes place above ground, cotlyedons are pulled above ground

Hypogeal germination takes place beneath the surface with cotyledons also remaining below ground.

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36
Q

Give one plant example of epigeal germination

A

Phaseolus vulgaris - french bean

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37
Q

Give one plant example of hypogeal germination

A

Vicia faba - broad bean

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38
Q

State the equation for photosynthesis in words

A

light

carbon dioxide + water ——-> Carbohydrates + oxygen

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39
Q

DEfine photosynthesis

A

The process by which plants use energy from light to convert carbon dioxide and water into food and oxygen

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40
Q

State the necessity for chlorophyll and light in photosynthesis

A

Sunlight provides the energy which is essential for photosynthesis to take place.
Photosynthesis primarily takes place in the chloroplasts of the pallisade mesophyl. It is in the chloroplasts that we find chlorophyll, the green pigment which drive the photosynthetic process by absorbing and storing the energy from sunlight and uses it to convert carbon dioxide and water into it into glucose

41
Q

List the environmental factors which affect the rate of photosynthesis

A 
Light intensity and quality 
Temperature
Water availability 
Nutrient availability
Co2 levels
42
Q

Describe how light intensity affects rate of photosynthesis

A

Light is the energy source that fuels the process and without it photosynthesis will not take place. Photosynthesis will increase up to a maximum level in line with the intensity, after this no further increase will take place

43
Q

Describe how Light quality affects rate of photosyntheis

A

Light has to be at the correct wavelength as chlorophyll only reacts to certain wavelengths

44
Q

Describe how Temperature affects rate of photosynthesis

A

Optimum temperatures for photosynthesis to take place is 25-30 degree. in some plants excessively high temperatures will slow the rate of photosynthesis

45
Q

Describe how Water availability affects the rate of photosynthesis

A

With insufficient water available the stomata will close to prevent water loss inhibiting the photosynthetic process

46
Q

Describe how nutrient availability affects the rate of photosynthesis

A

In correct quantities nutrients are required for photosynthesis, particularly magnesium, iron and nitrogen. These are used in the production of chlorophyll and so any reduction of these nutrients will slow down photosynthesis

47
Q

Describe how carbon dioxide levels affect the rate of photosynthesis

A

In closed environments such as a greenhouse Co2 which is essential for photosynthesis to take place is used by plants and may not not be replaced. Equipment can be used to generate carbon dioxide in these circumstances

48
Q

State the equation for aerobic respiration in words

A

Carbohydrate + oxygen——-> Carbon dioxide + water + energy

49
Q

State the equation for anearobic respiration in words

A

Glucose—— ethanol and carbon dioxide

50
Q

List the factors that affect the rate of respiration

A

Oxygen

Temperature

51
Q

Describe the significance of aerobic and anearobic respiration in horticultural situations

A

Waterlogging: causes anaerobic respiration, and the ethanol produced is toxic to most plants and may cause death

propagation:

produce storage:

seed storage : seeds can be kept in a viable state by controlling temperature and oxygen levels to reduce the respiration rate

52
Q

Distinguish between diffusion and osmosis

A

Diffusion is the mechanism by which plants absorb and release water, oxygen and carbon dioxide . Atoms or molecules move from an area of high concentration to an area of low concentration until they are evenly distributed

Osmosis is process by which water moves across a semi permeable membrane from a solution with higher concentration of water molecules to a solution with a lower concentration.

53
Q

Describe the pathway of water movement from the soil through the plant and into the atmosphere.

A

Water is absorbed from the ground by root hairs and epidermal cells by osmosis.
Having entered the cells of the epidermis by osmosis the water is pushed across the cortex as more water enters the plant.
the cells of the endodermis again push the water by osmosis into the cells of the xylem of the stem and through to other parts of the plant
The pushing effects of the epidermis and the endodermis is called root pressure, this is what helps push water a certain way up the stem.
Water is passed into the leaves and most of the water is lost through transpiration. Transpiration creates a pulling effect known as transpirational pull, that together with root pressure and the property of water that causes it,to cling together allows water to reach the heights required

54
Q

State what is meant by the term transpiration

A

Transpiration is the loss of water from the plant by evaporation, mainly through the stomata on the leaves.
The loss of water creates a pulling effect known as traspirational pull and enables water to be drawn up into the plant to reach the heights required.

55
Q

List the factors that affect the rate transpiration

A 
Light
temperature
humidity
wind
water uptake by roots
56
Q

Describe how the plant may limit water loss

A

Stomatal closure

Leaf adapatation :
HAIRS can help reduce the amount of water lost from leaves making the plant more drought tolerant and can also serve to protect them from cold.(salvia argentea)

THICK CUTICLES helps to prevent plants from drying out. (magnolia)

NEEDLES : Needles have a thick, waxy coating that retains more water than a regular leaf.
(coniferous trees- chamaecyparis lawsonia)

57
Q

Describe the uptake and distribution of minerals/nutrients in the plant

A

Nutrients come from weathering rock or from the breakdown of organic matter. These nutrients are dissolved in the soil water and absorbed through the roots. They are transported through the xylem and distributed through the phloem

58
Q

Describe how the internal and external structure of a leaf is designed to maximise photosynthesis

A

Structure:

Thin waxy cuticle; Only one layer of transparent upper epidermis; Several layers of palisade cells with many chloroplasts; large vacuole to push the chloroplast to the edge of the cell; Specialised pigments to maximise photosynthesis; Big intercellular air spaces for gaseous exchange.

External:

Big surface area to maximise the absorption of light; Petiole to hold lamina out into the light; Leaves move to face the sun.

59
Q

Describe how the internal and external structure of the leaf is designed to minimise transpiration. Draw diagram of a leaf showing stomata

A

Reduced leaf surface area, Leaf adapations, waxy cuticles, leaf hairs.

Stomata Closure: Stomata are mostly found on the under surface of leaves and are the main exit point of water from the plant They control water loss by closing at night (open during the day) also if the leaf wilts the stomata loses its turgidity and so will close (extreme mid-day heat can cause stomata to close).

Having fewer stomata; Having deep or extensive root systems; Having light, silver/grey foliage to reflect heat; Sunken stomata

60
Q

Describe the differences between conifers and flowering plants

A

Both plants reproduce sexually, but the way they hold onto their seeds is different.
Flowering plants also known as angiosperms, produce seeds which are encapsulated within the ovaries whilst conifers are gymnosperms. Gymnosperm translates to ‘naked seed’ and so conifers produce a seed which is not protected by an ovary but a cone. Conifers also mostly evergreen, woody perennials with needle-like or scaly leaves. Their stems are woody and their vascular bundles are arranged to form complete rings around the stem.
Flowering plants vary greatly, they can be evergreen,deciduous, herbaceous or woody. Their life cycle is dependent on the plant and can be annuals, ephemeral, biennials, perennial. Their flat leaves come in many shapes and sizes but ultimately they will be classified into groups of monocot or dicot.

Bulletpoint:
Confiers :
-Mostly evergreen, perennials
-gymnosperms producing naked seed not enclosed by an ovary but a cone.
-Needlike or scaly leaves
-Woody stems with vascular bundles arranged to form complete rings around the stem

Flowering:

  • Can be evergreen, deciduous, herbaceous or woody.
  • flowering plants can be any of the life cycles- is plant dependent
  • Angiosperms, producing seed which is encapsulated within the ovary
  • herbaceous flowering plants have vascular bundles which are scattered and spread out
  • leaves are flat and differ greatly in size and shape.
  • flowering plants are divided into groups of monoct or dicot
61
Q

Describe the differences between monocotyledons and dicotyledons

A

Flowering plants are divided into groups of monocotyledons and dicotyledons,
The root, stem and leaf structure determine the classification.

Monocots: 
Fibrous root system
Scattered vascular bundles in stem
Has one cotyledon (seed leaf)
Leaves are narrow and strap like with parallel venation

Dicots
Tap root system
Vascular bundles arranged complete rings around the stem
2 cotyledons
Broad leaves with a reticulated venation (network of veins )

62
Q

State the reason why botanical names are so important

A

Botanical nomenclature allows for unique identification of every single plant and is recognized internationally. This offers stability and effective communication where common names can often cause confusion

63
Q

Describe the binomial system of naming plants

A

The botanical name is made up of two parts. The Genus, which always begins with a capital letterand is written in italics represents a group of plants with similar characteristics. The species, the second part of the botanical name is written in lowercase italics and represents a sub group of one or more plants within a genus. They also have similar characteristics.

Example
Aucuba japonica
Papaver orientalis
Quercus robur

64
Q

Describe the meaning of cultivated plants

A

Within a species there can be variations which require separate identification. These variations occur either naturally through cross fertilization or genetically through deliberate breeding of plants.

A naturally occuring variation is known as a variety and is written as Genus species var. The variation is then written in lowercase
Example:
 Quercus robur var. fastigiata
Camellia japonica var. pleniflora
Rosa rugosa var. alba
A genetic, purpose bred variation is known as a cultivar and is written in quotations following the species. The cultivar always begins with a capital letter
Example:
Astrantia major ' Alba'
Taxus baccatta ' Fastigiata'
Aucuba japonica ' Variegata'
65
Q

Describe the stages of the life cycle of a plant

A

Seed : plants start life as an embryo within a seed. When conditions are suitable the seed will germinate and produce its first seed leaf/leaves

Juvenille: This is the vegetative growth period, this stage can vary from weeks to years and during this stage the plant is unable to produce flowers and therefore cannot reproduce

Adult: The reproductive stage, this covers the longest period of its growth cycle. The plant continues to grow and is now capable of producing flowers and fruits and is able to reproduce.

Senescence: This stage represents a plants old age. Plant processes slow down until growth and flowering stop

Death: Senescence leads to the death of the plant. All plant growth and production have completely stopped and the plant begins to decay.

66
Q

Define botanical term annual and give example of two annual plant

A

Annuals are herbaceous plants which complete their life cycle in one year
Pisum sativum
Verbena bonariensis

67
Q

Define botanical term ephemeral and give example of two ephemeral plant

A

Ephemerals are herbaceous plants which are short lived but have many cycles in a year

Cardamine hirsute
Senecio vulagris

68
Q

Define botanical term biennial and give example of two biennial plant

A

A herbaceous plant which completes its life cycle in 2 years. Vegetative growth dominates the first year and flowers follow in the second.

Digitalis purpurpea
Bellis perennis

69
Q

Define botanical term Perennial and give example of two perennial plant

A

Perennials are those that have a life cycle lasting 2 years or more

Alchemilla mollis
astrantia maxima

70
Q

Define botanical term herbaceous

and give example of two herbaceous plants

A

Herbaceous plants have soft tissues and do not develop woody structures. Their stems and leaves usually die in winter
Alchemilla mollis
astrantia maxima

71
Q

Define botanical term woody

and give example of two woody plant

A

Woody plants produce wood as its structural tissues, they have a permanent branch structure and survive winter above ground. Trees, shrubs and conifers are all woody plants
aucuba japonica
camellia japonica

72
Q

Define botanical term evergreen

and give example of two evergreen plant

A

Evergreens are mostly woody plants that retain their leaves throughout all seasons. There are few perennials that are evergreen retaining some leaves at the base of the plant.

aucuba japonica
camellia japonica

73
Q

Define botanical term semi evergreen

and give example of two semi evergreen plant

A

Semi evergreens are woody plants which can retain their leaves in milder winters. The milder the winter the longer the leaves will retain.

acanthus mollis
allium

74
Q

Define horticultural term tender perennial

and give example of two tender perennial plant

A

Tender perennials are usually herbaceous and cannot survive frosts. They are often placed inside during winter and early spring to provide protection and transplanted after last frosts.
Fuchsia magellanica
Pelargonium

75
Q

Define horticultural term half hardy annual

2 examples

A

Half hardy annuals are herbaceous plants which are sown early in the season under protection and then planted after the last frosts. They will complete their life cycle in 1 year

cosmos
zinnia

76
Q

Define horticultural term hardy annual

2 examples

A

Hardy annuals are sown directly outdoors early in the season where it is to flower and is most likely able to survive the first spring frosts. They will complete their life cycle in one year

nasturtium
calendula officinialis

77
Q

Define term tree and give 2 examples

A

Trees are woody perennials that usually have one main stem/trunk with many branches above forming a crown. They are mostly deciduous but some are evergreen

quercus robur
fraxinus excelsior

78
Q

Define term shrub

2 examples

A

A shrub is smaller then a tree and has multiple stems arising from ground level or has a a very short main stem. Shrubs can be either evergreen or deciduous and are mostly woody however some may have herbaceous top growth
camellia japonica
aucuba japonica

79
Q

List contents of a typical plant cell

draw a typical plant cell

A 
Cell wall
cell membrane 
chloroplast
cytoplasm
nucleus 
mitochondria
vacuole
80
Q

State function of cell wall

A

The cell wall contains and surrounds the entire contents of the cell. It is made of cellulose which is permeable allowing liquid and gas to pass through

81
Q

state function of cell membrane

A

The cell membrane is a thin sheet within the cell wall that encloses the cytoplasm and controls the movement of substances in and out of the cell

82
Q

state function of chloroplast

A

Chloroplast exists in great numbers in the cells of leaves (and green parts of plant). Containing a pigment called chlorophyll which gives plants their green color and is where photosynthesis takes place

83
Q

state function of cytoplasm

A

Cytoplasm is a jelly like substance which fills the cell within the cell membrane. The cellulose gives each cell its structure which helps plants to remain sturdy and upright

84
Q

state function of nucleus

A

The nucleus is the control center or the ‘brain’ of the cell. It contains genetic information (DNA) which will determine the characteristics of the plant

85
Q

state function of vacuole

A

The vacuole is a sac surrounded by its own membrane that contains water, minerals and waste product. The pressure of the liquid against the membrane helps with structural support of the plant

86
Q

state function of mitochondria

A

Mitochondria exists in all parts of the plant and is fundamental for the respiration process which provides energy for the plant to grow.

87
Q

Describe where cell division takes place

A

New cells are produced in the meristem.
Meristems occur in two areas; the apical meristem and the lateral meristem.

The primary growth occurs in the apical meristem near the tips of roots, stems and buds. The apical meristem is responsible for the lengthening of the plant and allows leaves and flowers to differentiate

The lateral meristem found in the stems and roots is responsible for secondary growth. A thin band of cells between the xylem and phloem called the vascular cambium produces new xylem and phloem cells. it is this which causes the secondary thickening of the plant

88
Q

Describe how plants increase in size

A

All plants grow by means of cell division, this process of one cell dividing into two is known as mitosis and it occurs in meristematic regions of the plant. The primary growth in the apical meristem is responsible for the lengthening of a plant and in woody plants, the secondary growth in lateral meristem is responsible for the thickening of the plant.

89
Q

State what is meant by plant tissue

A

Plant tissue is a collection of similar cells performing a specific function for the plant. Each plant tissue is specialized for a unique purpose and can be combined with other tissues to create organs such as leaves, stems, flowers and roots.

90
Q

Describe the characteristics and functions of the Epidermis

A

The epidermis consists of tightly packed cells which cover the plant entirely like skin. It is usually one cell thick and acts as a protective barrier against injury, water loss and infection

91
Q

Describe the characteristics and functions of the cambium

A

The main job of the cambium is to promote growth of secondary xylem and phloem. It’s located directly between the primary xylem and phloem in a circular layer. Typically, dicot plants or gymnosperms have cambium tissue

92
Q

Describe the characteristics and functions of the phloem and xylem

A

Both xylem and phloem are part of the lateral meristem. The xylem transports water and minerals from the roots of the plant up through the stem and into the leaves. The cells are short lived and as they become lignified, produce strength and support to the plant. (lignified cells constituted the wood in plants)
Phloem consists of living cells which pass food from cell to cell allowing it to reach all parts of the plant.

93
Q

Describe the characteristics and functions of parenchyma

A

Parenchyma is found in all parts of the plant. They are permanent tissues which contribute to the bulk of the plant. Their function is to store food , nutrients and water and also for photosynthesis and respiration.

94
Q

Describe the function of roots

A

Roots provide anchorage for plants, holding them firmly in the soil.
Take water and nutrients from the soil
Some roots have adapted to provide storage for food
or can even be a means for reproduction.

95
Q

Describe the root types

A

Tap roots have one main root with smaller, fine roots branching from it. They originate from the radicle and can extend deep into the soil. Most trees and shrubs have tap roots

Fibrous roots are multi branched and originate from the base of the stem, They are shallowly rooted and rely on water drainage from the surface

Adventitious roots are those that grow from other parts of the plant, usually a stem but can also grow from a leaf. This type of root is most often seen in climbers or plants that produce runners. These roots help plants to climb or provide a support/prop.

96
Q

Describe the differences between monocotyledonous and dicotyledonous roots

A

Whilst the tissues of monocot and dicot roots are vary similar they differ in arrangement. In monocot roots the vascular structures are arranged in a circular pattern around the central pith. Their roots are fibrous or adventitious

Dicot roots show a tap root system which penetrates deep into the soil. Their vascular bundles are located in the middle of the root, surrounded by vascular cambium.

97
Q

Describe the structure of the root and state the function of its components

A

The main parts of the root include the

ROOT CAP , a layer of cells on the surface of the root tip which protects it as it grows and pushes through the soil.

The APICAL MERISTEM is a region of cells capable of cell division and is responsible for the lengthening of the roots.

(The root cap and apical meristem together constitute the are of cell division)

The ROOT HAIRS are small thread like structures growing from the epidermal cells close to the growing tip. The hairs increase the surface area assisting in water and nutrient uptake.

The EPIDERMIS is the outer layer of cells which provides protection and helps in absorption. The root hairs are extensions of epidermal cells

The CORTEX is a thick layer of cells which produce energy for the growth of the root and are used for storage. water and nutrients can pass through/between these cells

The ENDODERMIS are the innermost cells of the cortex and control the movement of water and nutrients from the cortex into the xylem.

Pericycle

PHLOEM is the tissue which transports food made in the leaves to other parts of the plant

XYLEM is the tissue that transports water and nutrients absorbed by roots to all other parts of the plant.

98
Q

Describe how the root has adapted to perform other functions

A

Roots have adapted in different ways, Hedera has adapted adventitous roots which help it to climb, whilst dahlias and veg like Daucus carota has root tubers beneath the ground for food storage and perennation. Another example of root adaptations can be found in zea maiz where prop roots help to give the plant support and stability.

Rhs r2101 (1 decks)

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