Plant Structure Flashcards
Draw a structure of flowering plant
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What are the two portions of a plant?
Over ground shoot system and under ground root system
What are the parts of a plant
Apical bud, flower, stem, leaf, axillary bud, fruit, petiole, node, internode, node, primary (or tap) root, lateral (or secondary) root.
What is a meristem
An area of active cell division
Where are apical meristems found?
at the tip of the shoot and tip of the root and give an increase in length.
Where are lateral meristems found?
around the edges of some plants and give an increase in width
What are the functions of roots?
Anchor, absorb water, absorb minerals, transport absorbed materials to shoot, store food.
What are tap roots?
One main root growing from the radicle e.g. carrot
What are fibrous roots
Many equal sized roots arising from stem base e.g. grass
How many types of roots are there?
2
What are the four root zones?
Differentiation zone, elongation zone, meristematic zone, protection zone.
draw a diagram of a root
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What happens in a differentiation zone?
Cells develop into 3 different types of tissue
What happens in an elongation zone?
Here cells increase in size
What happens in a meristematic zone?
Here new cells are produced by mitosis divisions
What happens in a protection zone?
A root cap protects the cells as the root pushes through the soil
Draw a transverse section of tissue location in a root
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Name the tissues in the root
Dermal Tissue, Xylem, Vascular Tissue, Phloem, Ground Tissue
Draw a longitudinal section of the root
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What are the functions of the stem?
Support the arial parts of the plant.
Transport water and minerals from roots to leafs.
Transport food from leafs to roots.
Sometimes store food
What are the functions of outer stem parts?
Terminal Bud - increase stem length
Lateral Bud - Grow side branches
Lenticels - Gas exchanges
Draw a diagram of a transverse section of tissue location in a stem.
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Name the tissues in a stem
Dermal tissue, Xylem, Phloem, Ground tissue, Vascular tissue.
What are the functions of a leaf?
Photosynthesis, transpiration, gas exchange, sometimes store food.
What are the two types of cell in xylem?
xylem tracheids and xylem vessels
Where are xylem tracheids found?
conifers
Where are xylem vessels found?
deciduous trees
What are xylem cells like on maturity?
On maturity both are dead, hollow and contain no cytoplasm
Describe a xylem tracheid structure
Long cells tapered at both ends
Pits in the walls - allow water and minerals to mover sideways from cell to cell
Walls thickened with lignin for support
Draw a xylem tracheid structure
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Draw a xylem vessels structure
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Describe a xylem vessels structure
Elongated cells
Spiral lignin for strength
No end walls - form a continuous tube
Pits to allow sideways movement of water
What are the two types of cell in a phloem structure?
Sieve tube cells and companion cells
Draw a diagram of a phloem structure
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What does the nucleus control in phloem?
the activities of both companion and sieve tube cell
What happens to cytoplasm in phloem structure?
Cytoplasm extends from cell to cell through the sieve plate
What is different about mature cells
mature cells have no nucleus
name the plates in a phloem structure
sieve plates
What is an example of a monocot?
grass
What is an example of a dicot?
buttercup
What is the number of cotyledons that monocotyledons and dicotyledons have?
Monocots = one Dicots = two
What is the arrangement of vascular bundles in the stem of the monocot and dicot like?
monocot = scattered in the stem dicot = in a ring pattern
What is the leaf venation of a monocot and a dicot like?
monocot = parallel dicot = netted
What is the number of flower parts in a monocot and a dicot?
monocot = in threes dicot = In fours and fives
Are monocots and dicots woody or herbaceous?
Monocot = Almost all are herbaceous Dicot = May be woody or herbaceous
What does an autotrophic organism do?
It makes it’s own food
How do plants make their own food?
photosynthesis
Why do plants need a transport system?
To provide the materials needed for various plant metabolic processes including photosynthesis, respiration, growth and reproduction.
What materials are transported in plants?
Water, carbon dioxide, minerals, carbohydrates produced in photosynthesis
How does water enter the root hair cells?
By osmosis
How are root hairs adapted to the process of osmosis?
By having thin walls and a large surface area
Draw a diagram of water moving through a plant
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How does water move through a plant?
By diffusion from the root hairs into the ground tissue and eventually reaches the xylem
What do xylem form from roots to leaf?
continuous hollow pipes
Draw a diagram of water entering the root, labeling the root hair, ground tissue and xylem
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How many mechanisms cause upward movement of water through the stem in the xylem and what are they called.
Two mechanisms combined to cause upward movement of water through the stem in the xylem - root pressure and transpiration.
How does root pressure cause upward movement of water through the stem in the xylem?
As water moves into the root by osmosis it builds up a pressure that pushes water up the xylem
How does transpiration cause upward movement of water through the stem in the xylem?
As water evaporates from the leaf by transpiration, more water is pulled upwards through the xylem and into the leaf
Draw a diagram of xylem vessels and tracheids.
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Draw the transpiration stream
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What is it called when water evaporates from the leaf cells?
transpiration
What does transpiration create in a plant?
an osmotic gradient
What happens to the leaf cells in a plant when an osmotic gradient is created?
They become less turgid
What does the leaf cells in a plant becoming less turgid due to an osmotic gradient being created cause?
Water to move out of the xylem to the leaf cells
What controls the water loss from a leaf?
The presence or absence of a cuticle and the opening and closing of the stomata
How does the opening and closing of the stomata control the water loss from a leaf?
Stomata closing reduces water loss
Stomata opening increases water loss
How does the presence or absence of a cuticle control the water loss from a leaf?
Water cannot pass through the cuticle. The presence of a cuticle helps reduce excessive loss of water.
What are examples of mineral uses in a plant?
Calcium helps make cell walls
Magnesium is part of chlorophyll
How are potassium, nitrates and phosphates absorbed and transported?
They are absorbed by active transport which requires energy. They are transported from the roots in the xylem, dissolved in water
What are carbon dioxide sources in a plant?
Produced in the leaf during respiration
Diffuses from the air in through the stomata
Name two photosynthesis products
Glucose and oxygen
How is glucose used in the plant?
Glucose is converted to starch and glucose and starch are transported in the phloem
How is oxygen used in the plant?
Oxygen is transported through the air spaces and out through the stomata by diffusion
Give an example of a root modified to store food
carrot
What do dicot plants produce, give an example
Dicot plants, e.g. carrots, produce one main tap root
What happens to the one main tap root of a dicot plant?
It becomes fleshy and swollen with stored starch
What is an example of a stem modified to store starch?
Potato
What stem system do potatoes have?
An underground stem system
What happens to the tips of the stems of potatoes?
What are the swollen stem tips known as?
The tips of these stems become swollen with stored starch. They are known as tubers.
What are the parts of a potato tuber?
Apical bud, lenticel, lateral bud
draw and label a potato tuber
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Give an example of a leaf modified to store food?
onion bulb
What part of a plant is an onion bulb?
A reduced underground stem
What are the leaves of the onion bulb like?
fleshy and swollen with stored starch
What are the leaves of an onion bulb surrounding?
a central apical bud
What are the parts/features of an onion bulb?
dry scaley leaves, fleshy leaves, apical bud, reduced stem, adventitious roots
What does the cohesion-tension model of xylem transport do?
Explains how water is transported in plants to extreme heights against the force of gravity
Who proposed the cohesion-tension model of xylem transport?
Henry Dixon and John Joly
Where did Henry Dixon and John Joly work?
Working in Trinity College 1894
What does cohesion mean in terms of the cohesion-tension model of xylem transport? Give an example.
Similar molecules sticking together e.g. water sticking to water
What does adhesion mean in terms of the cohesion-tension model of xylem transport? Give an example.
Different molecules sticking together e.g. Water sticking to xylem walls
What is the first stage of the cohesion-tension model of xylem transport?
Cohesion between water molecules in the narrow xylem tubes causes the water to form into a continuous column or stream in the xylem.
What is the second stage of the cohesion-tension model of xylem transport?
As water molecules evaporate in transpiration at the leaf cohesion between the water molecules replaces the water by pulling the next water molecule up the xylem`. As the column is hard to break this pull is felt down the entire column of water to the root.
What is the third stage of the cohesion-tension model of xylem transport?
Transpiration from the leaf puts the column of water under tension tension can pull a column of water to great heights in plants.
What causes the column of water to be stretched?
tension
What prevents the column breaking?
Cohesive forces between the water molecules are strong enough to prevent the column breaking.
What prevents the xylem from collapsing in?
lignin in the walls
What is sensitivity?
The ability to detect change and to respond is called sensitivity.
Response
Response is a form of defence that allows organisms to survive.
How do plants adapt to new situations?
Plant adapt to new situations by modifying their growth by means of chemicals called growth regulators [hormones]
What is growth?
Growth is the increase the number, size and volume of cells.
What is a hormone?
A hormone is a chemical produced in one part of an organism, transported to other tissues where it has its effect.
What are external factors that regulate the growth of plant?
External factors that regulate the growth of plants are light intensity, day length, gravity, temperature.
What is development?
Development means the changes that lead to specialised tissues and organs.
In what way are plant growth regulators active?
They are active in very small amounts
Where are plant growth regulators produced?
They are produced in the meristems
Where are plant growth regulators transported?
In the xylem and phloem
What are plant growth regulators effects dependent on?
Their effects are dependent on concentration
What can have a great effect on the growth of a plant?
A small amount of growth regulator can have great effect on growth
What is a coleoptile?
The sheath around the leaves and shoot of grass seedlings, such as corn or oats.
What is a trophism?
A plant’s response to a stimulus coming from one direction, e.g. sunlight, gravity
Phototropism
is a growth response of a stem towards light
Geotropism
is the growth of a plant in response to gravity
Thigmotropism
is the growth of a plant in response to contact
Hydrotropism
is the response of roots to water - they will grow towards it.
Chemotropism
is the plant’s response to chemicals
What do auxins do?
promote cell enlargement and growth and are involved in phototropism and apical dominance
How does phototropism work?
In shoots, light causes auxin to move down the shaded part of the stem, causing the shoot to grow towards the sunlight
What can artificial auxins be used for?
Artifical auxins can also be used to kill weeds, stimulate roots formation in cuttings.
Draw a diagram of the effect of auxins on phototropism
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What do gibberellins do?
Cause stem lengthening, mobilise the stored food in germinating seeds and break dormancy in buds and seeds in spring
What do cytokinins do?
Stimulate cell division (mitosis) and trigger leaf growth in spring
What does abscisin do?
Abscisic acid triggers bud and seed dormancy in autumn and inhibits cell growth.
What does ethene do?
Ethene promotes ripening of fruit and the fall of leaves, flowers and fruits.
How are artificial auxins used in rooting powders?
Artificial auxins are used in rooting powders to stimulate root formation in stem cuttings
How is a synthetic auxin used as a selective weedkiller?
A synthetic auxin [2, 4-D] is used as a selective weedkiller, making the plants grow too fast.
How is fruit transported unripe and then quickly ripened?
Fruit is transported green unripe, and can then be quickly ripened by spraying it with ethene.
What are two ways plants can adapt themselves for protection in two ways?
- Structural or anatomical adaptations
2. Chemical adaptations
What is bark/epidermis structurally adapted to do?
Prevents entry of microbes and reduces loss of water
What is a thick cuticle structurally adapted to do?
a thick cuticle on stem or leaves to prevent loss of water in plants that live in dry places
What are thorns structurally adapted to do?
Thorns prevent plants from being eaten by herbivores
What is a stinging cell structurally adapted to do?
Stinging cell in epidermis prevent plants being eaten
What are guard cells structurally adapted to do?
Guard cells change shape when they lose water which causes stomata to close and this reduces water loss.
What are Tannins chemically adapted to do?
Production of Tannins to make the plant indigestible
What are toxic chemicals chemically adapted to do?
Production of toxic chemicals to prevent growth of insect larvae
What are strychnine and nicotine chemically adapted to do?
Production of strychnine and nicotine in legumes that damage nerves and muscles
What are heat shock proteins chemically adapted to do?
Production of heat shock proteins to protect enzymes when temperatures are high
What is plant’s most important adaptation?
Plants can grow and regenerate throughout their life. They can produce new roots, stems, leaves.
What do auxins promote?
Promote cell enlargement and growth.
What are auxins involved in?
Are involved in phototropism - stem bends towards light
What are auxins responsible for?
Responsible for apical dominance, where the main bud inhibits the growth of buds lower down stem.
What do auxins regulate?
Regulate the differentiation of the vascular tissue (xylem and phloem)
What is the most abundant naturally-occuring auxin?
Indole-3-acetic acid (IAA) is the most abundant naturally- occuring auxin.
What is IAA?
IAA (Indoleacetic acid) is an auxin that is made in the meristems of shoots, buds and root, and in the tips of coleoptiles [of grasses].
How does auxin travel and what happens to it?
Auxin travels backwards from the tip in the vascular tissue and causes cells to elongate (get longer).
What does the cells elongating due to auxin cause?
This makes the zones of elongation grow and so the tip is pushed further upwards (in shoots) and downwards (in roots)
What is elongation caused by auxins movement caused by?
Movement is by active transport from cell to cell, this requires energy.
