Lecture 12 Plant Sciences/ Physiology Flashcards
What is the outer cell wall of a plant cell made of?
Cellulose- a strong substance able to withstand the pressure of moving fluids and nutrients without expanding
Comment on the role of transport proteins within the cell membrane.
Transport proteins aka carrier proteins located within the cell membrane, form a channel to allow substances such as sodium, potassium, sugars, proteins and messenger molecules to pass through. They make every from communication to cellular metabolism possible.
Why are chloroplasts so important?
Chloroplasts are the organelles where photosynthesis take place. They contain the pigment chlorophyll which is necessary for photosynthesis. Chloroplasts also store nutrients (starches).
Why is it important to avoid plants wilting?
Wilted plants rapidly lose nutrients. Harvesting, drying and storing plants is an art that aims to prevent the loss of nutrients and medicinal properties. Plants are best dried in a warm, dry place, or in the sun, then stored in cool dark place.
How can you naturally boost your magnesium consumption?
Eat leafy greens. Plant cells contain a green pigment, chlorophyll which is a valuable source of magnesium.
What are some of the benefits of consuming pectin?
Pectin is contained in a layer of cells in the middle lamella and glues cells together thus making them more stable.
Pectin has demulcent properties which heal the gut lining and bind to toxins and cholesterol (preventing absorption).
Thickens jams making them jelly-like
What type of tissue is chiefly responsible for growth? Describe the different types.
Meristemic tissue is rapidly dividing
Two types: apical and auxiliary
Cork Cambium- tube of meristemic tissue runs length of roots and stems in outer layer of woody plants, thickens
Lateral meristem- tube along roots and stems causing widening/ secondary growth
What is meant by Parenchyma? What are the different types.
Parenchyma are tissues with the following attributes:
thin-walled
unspecialised
abundant
rapidly-diving
adaptable to various f(x)’s via differentiation
Chlorenchyma- contains chlorophyll
Collenchyma- flexible support
Schlerenchyma- nut shells, fibers structural support
Aerenchyma- pockets of air in cells allowing for gas exchange. Common in aquatic plants
Describe the function of the following types of parenchyma:
Chlorenchyma
Collenchyma
Schlerenchyma
Aerenchyma
Chlorenchyma- photosynthesis
Collenchyma- gives flexible support (celery)
Schlerenchyma- strong structural support like in nut shells including fibres
Aerenchyma- have pockets of air allowing for gas exchange and flotation in aquatic plants
What are the functions of Xylem?
Xylem is a complex plant tissue that forms part of the circulatory system for the plant it is centrally located and transports fluid up the roots. Walls are reinforced with lignin and there are no end-walls between cells.
Found in roots, stems, leaves
What are the functions of Phloem?
Phloem forms part of the circulatory system of the plant. It is located peripherally to the xylem and consists of large tube-like cells with pores in end sieve plates, allowing cytoplasm to pass freely.
Transports glucose from leaves to all cells
Lose nuclei at maturity and depend on a smaller companion cell to regulate activity hence always found as a double cell.
What is the function of the Epidermis?
The Epidermis is a protective outer covering modified by environment
Normally one cell thick but may be several layers to prevent desiccation
Secrete cutin which forms a protective cuticle
Why is sap important to us?
Sap is the substance transported by the xylem carrying minerals and important antiseptic medicinal properties
In woody plants the epidermis is replace by ______. The waxy substance _____ dies leaving a bark layer.
Periderm
Suberin
________lack suberin and allow for gas exchange with interior of the stem.
Lenticels
What is important about Osmosis for plants?
What force balances “osmotic potential”?
Osmosis is how plants draw water and nutrients into and out of cells to keep themselves alive and growing.
Turgor pressure- the pressure exerted by water in a cell against a cell wall
What is meant by Transpiration?
Transpiration is the loss of water by evaporation from plants from leaves and lenticels into the atmosphere.
It is a cooling mechanism that increases with temperature.
Up to 1000L of water may be transpired daily by mature trees in hot summer months
What is the function of the Casparian Strip?
A single layer of waterproof waxy suberin-impregnated cells that form a regulatory barrier in the endodermis that forces fluids to pass through plasma membranes of cells and also filters out harmful substances.
What causes the droplets to appear on Lady’s Mantle leaves?
Guttation describes the process whereby water is forced out of leaves due root pressure.
When is the best time of day to harvest plant material and why?
After the morning dew but before the heat of the sun to prevent loss of fluids and essential oils.
What are stomata? What special type of cells are associated with this plant structure?
Stomata are openings found in leaves and stems where water exits and carbon dioxide and oxygen can diffuse.
Guard cells surround stomata by pairs. When turgid by the inflow of water, the stomata opens. When flaccid stomata close thus preventing water loss at night or drought.
What is another name for plant hormones?
Phytohormones
In which plant tissue are Auxins produced?
Auxins are produced in the apical meristem at the tips of shoots in plants
Why is Gibberellic acid important particularly in medicinal herbs?
GA causes cell elongation, cell division and lengthening of internodes and rapid stem growth.
Emphasis on vegetative growth over fruiting and provides prolific leafy material for herbal use.
Do you think the use of hormones in horticulture and agriculture is safe?
No, synthetic GA used in commercial fruit to increase the size of table grapes and regulate citrus flowering and rind maturation, is shown to cause cancer in animal tests.
We don’t know enough about Nature to interfere at the level of hormones
.
Which plant hormone causes leaves to die and fall?
Abscisic acid
Explain why many plants grow in a cone shape.
Auxins in the apical tip, stimulate ethylene (a growth inhibitor) production which inhibits ancillary bud growth. But as it goes down, growth is allowed to go out again. Typical Christmas tree shape.
Which plant hormone is antagonistic to auxins in that they lead to lateral bud growth.
Cytokinins
This hormone inhibits longitudinal growth, promotes lateral growth and is involved in abscission (shedding of fruits and leaves)
Ethylene
What are the advantages of asexual reproduction?
Describe how knowledge of this can be useful in growing plants.
Advantages of asexual reproduction include
Give ONE method by which insect-pollinated plants avoid self-pollination.
This can be achieved by
What are the FIVE stages of germination?
1.
What elements do seed need in order to germinate?
Water,
What is the advantage to a plant of productions fruits?
Stores
Explain how sunflowers turn towards the light.
Sunflowers turn to face the sun (phototropism/ heliotropism) due to the accumulation of auxin on the shaded side of stems causing the cells to stretch.
What is meant by Gravitropism?
Gravitropism
Growth response to gravity
Positive Gravitropism- roots grow downwards
Negative Gravitropism- shoots grow upwards
Caused by gravitational movement of starch grains in root cap and stem tip cells.
Give a simple explanation of Photosynthesis and explain why it is important for life on earth.
Photosynthesis is a plant process where carbon dioxide, water and light energy are converted into carbohydrates producing oxygen as a by-product.
Without plants there would be very little oxygen to sustain human and animal life. Existence would be confined to bacteria and other organisms that can respire using sulphuric and nitrogen. Sequesters carbon dioxide.
Why do leaves turn yellow in the Autumn?
Yellowing leaves are due to the breakdown of Cholorphyll in the Autumn allowing the yellow/ orange carotenoid pigments to be revealed.
What does the similarity between haemoglobin and chlorophyll discuss the benefits of eating green plants?
The chemical composition of haemoglobin and chlorophyll are very similar making them excellent blood-builders.
Do plants respire? Explain respiration and how it is affected by certain conditions.
Yes, all plants get the energy they need to live on from a chemical reaction called respiration. Plant cells like animal cells use oxygen and produce carbon dioxide. Not dependent on light and dark levels like photosynthesis.
Respiration rate is affected by:
Temperature
Water
Oxygen
What are the advantages of asexual reproduction? Describe how knowledge of this an be useful in growing plants.
In asexual reproduction there is no need to find/ grown near a mate, saves energy as less pollen and nectar is produced.
Can grow plants from cuttings by putting them in water
Give ONE method by which insect-pollinated plants avoid self-pollination.
Adaptations apply for insect-pollinated plants to avoid self-pollination:
1-Dioecious flowers (male and female parts on separate plants)
2-Anthers (male organs) mature at a different time to the stigma (female organ)
3-Stigma and stamens arranged such that pollinating insect puts pollen of a previous flower onto the stigma before touching stamens.
What are the FIVE stages of germination?
Water Enzymes Respiration Radicle (root) then Plumule (shoot) emerge Leaves
What elements do seed need in order to germinate?
Moisture Drainage Correct Temperature Light or darkness Protection (from predators, drying, mold, excessive moisture)
What is the advantage to a plant of producing fruits?
Animals eat the fruit. The seeds survive the intestinal tract and then deposited by the animal (with a bit of fertilizer) to a new location.
What are the differences between plant and animal cells
Plant cells have chlorophyll (which is Mg-rich)
Cellulose plant cell wall- necessary for us
Lignified- impregnated with lignin which you see in woody plants
Similarities of plant and animal cells
Cell membrane (plasma membrane)
Nucleus and contains transport proteins in nuclear envelope
Transport proteins
Endoplasmic reticulum
Smooth- lipid and carbohydrate production, calcium storage
Rough- synthesis, storage and recycling of proteins
Chloroplasts (not animal) contains chlorophyll
Mitochondria- cellular respiration mobile
Golgi- transfers and modifies proteins in cell
Vacuole up to 90% cell volume, maintains cell pressure and contains chemicals, proteins and hormones. if water escapes, plant wilts
Cytoskeleton network of microtubles and filaments allowing movement of organelles
Cytoplasm basic cell solution, gel
Plasmodesmata strands of cytoplasm extending through cell walls connecting them allowing communication
Middle lamella- made of pectin glues cells together giving stability. Helps with leaky gut binds to toxins particularly. Hawthorn berries are very high pectin
What structure separates xylem from phloem?
Vascular cambium- a water proof layer preventing confusing between upward and downward movement
Discuss at least 3 specialised plant tissues
Hairs- protective tubular
Glands- modified epidermal cells for secretion
Epidermis- protective, normally once cell thick sometimes several layers
Cutin secreting cells protects forming cuticle
Draw a flow diagram illustrating the passage of water from plant root to leaf.
Water-> Epidermis>Plasmodesmta-> Cortex->Endodermis-> Casparian strip->Pericycle-> Xylem
What are the two mechanisms that assist transportation from roots to leaves by capillary action
Cohesion tension- water molecules polar charges
Water potential- water loss by transpiration and by knock on effect pressure change water below comes up to replace it
What are the two types of plant hormones-
Growth: Auxin, Cytokinins, Gibberellins
Inhibitory: Ethylene (but promotes lateral growth), Abscisic Acid
Auxin use
Commerical- promotes growth, uniformity
Synthetic- herbicide, Agent organic very toxic!
Give an example of a plant that exhibits growth movement
Mimosa pudica
What is photoperiodism, thermoperiodism
Effect of sun on plant
Effect of temperature on plant
Give an explanation of sexual reproduction (cross fertilization).
The pollen of one plant fertilises the stigma of another plant, thus combining the genes of two parents.
Describe the various seed distribution modification.
Wind distribution
Sepal (outer structure of flower) modification (form parachute structure- dandelion)
Attachment to animals
Floating on water due to trapped air or waxy waterproof layers
Ejection on spring like structures
Animal distribution following fruit ingestion and evacuation (symbiosis of plants and animals)
Draw a seed structure and label all parts
Seed coat
Hilum
Micropyle pore
Cotyledon (embryonic leaf , mono and dicotyledon)
Endosperm like the sac of egg
Embryo- part that will form seedling following germination- radical (root) and plumule (shoot)
Apical dominance is:
Select one:
a. The tendency of plants to grow upwards
b. The tendency of plants to follow the sun Incorrect
c. The tendency of plants to grow sideways
d. The tendency of plants to grow downwards
A. The tendency of plants to grow upwards
Plasmodesmata have which important function:
Select one:
a. Transport of nutrients from internal to external environments
b. Communication and translocation of substances between cells
c. Transport of fluids from roots up to leaves
d. Catalyse photosynthesis in chloroplasts
B. Communication and translocation of substance between cells
Which of the following is true:
Select one:
a. Auxins stimulate root development in plants
b. Auxins are produced in the tips of shoots to promote growth
c. Auxins cause the leaves of the plant to fall in the autumn
d. Auxins escalate the reproductive cycle of the plant
B. Auxins are produces in the tips of shoots to promote growth
What is the correct definition of transpiration?
Select one:
a. The loss of water through evaporation from the leaves
b. The process of converting sunlight to glucose
c. The pressure needed to maintain hydration within the plant
d. The process of transporting water to the deeper layers of the plant
A
What is meant by Negative Phototropism: Select one: a. Roots grow away from the light b. Plants grow best in the night c. Sunflowers follow the sun d. Plants automatically grow towards the light
A
Why are animals important to plant propagation:
Select one:
a. Their hormones interact with plant hormones promoting growth
b. Their dung fertilises the plant
c. They help to keep the plants trimmed down
d. They eat the fruits and distribute the seeds on evacuation
D
The rate of respiration in plants is determines by: Select one: a. Temperature, pressure, light b. Water, pressure, CO2 c. Oxygen, CO2, Light d. Temperature, Water, Oxygen
D
What is the advantage of wind pollination:
Select one:
a. It prevents plants from growing directly beneath their parents
b. It strengthens the seeds of plants by stressing them out
c. It is good for plants growing in inclement conditions
d. The plant does not need insects
A
Which is true of Abscissic Acid:
Select one:
a. It aids the plant tin adapting to the seasons
b. It causes a shortfall of nutrients in the plant
c. It causes rapid growth in the Spring
d. It causes leaves to die and fall off
D
The function of Xylem is:
Select one:
a. To store nutrients
b. Divides the inner from the outer cambium
c. Transports glucose from the leaves to other parts of the plant
d. Transports fluids up from the roots
D
