Download Generally: Roots- Absorption of water and minerals, anchorage

Generally:
Roots- Absorption of water and minerals, anchorage, food storage (some more than others), reproduction (some).
Stems - Translocate water and minerals to the leaves; transport food (sap) downward from the leaves to the roots.
Leaves - the major photosynthetic (food making) organ of a plant.
Transpiration cohesion theory- Transpiration is the loss of water through the stomata in leaves. This loss of
water causes an area of low pressure within the plant- this is the tension part- and water moves from where it is
at high pressure to low pressure. The cohesion part is what allows water to do this against gravity. Because
water molecules are polar they have weak bonds between the molecules that are enough to cause a cohesive
force holding molecules together. With movement of water in the xylem i would also consider root pressure
(where water moving into the roots creates higher pressure and thus water goes up) and capillary action (where
water molecules climb on top of one another up the walls of xylem) on top of transipration pull.
Pressure Flow Hypothesis -known as the Mass Flow Hypothesis, is the best-supported theory to explain the
movement of food through the phloem.[1] It was proposed by Ernst Münch, a German plant physiologist in
1930.[2] A high concentration of organic substance inside cells of the phloem at a source, such as a leaf, creates
adiffusion gradient (osmotic gradient) that draws water into the cells. Movement occurs by bulk flow (mass
flow); phloem sap moves from sugar sources to sugar sinks by means of turgor pressure, also known as
hydrostatic pressure. A sugar source is any part of the plant that is producing or releasing sugar. During the
plant's growth period, usually during the spring, storage organs such as the roots are sugar sources, and the
plant's many growing areas are sugar sinks. The movement in phloem is bidirectional, whereas, in xylem cells,
it is unidirectional (upward).
Primary vs secondary growth: primary growth occurs at the apical meristems, where the structure is elongated
secondary growth occurs at the vascular cambium and cortex cambium, where the structure is increased in
width
Primary growth as it applies to the stem of a plant is simply the elongation of the stem. Both monocots and
dicots display primary growth as both plants elongate regularly throughout their life cycle (typically).
Secondary growth is the thickening of the stem. Monocots are broadly said to have no secondary growth. Many
dicots display extensive secondary growth and dicots are broadly said to display secondary growth commonly.
Monocot vs dicot stems The reason for the lack of secondary growth in monocots is due to the scattered
arrangement of xylem and phloem in the stem. The thickening of the stem would cause the xylem and phloem
to break in the stem and be non-continuous due to the uneven division of cells in the stem. Whereas dicots
have secondary growth as their xylem and phloem are arranged in a circular fashion which permits thickening
of the stem inside of the circular bundle of vascular tissue without causing the vascular tissue to break.
Breaking the vascular tissue of a plant would stop fluid and nutrient transport in Angiospems (which are
flowering plants that include all the monocots and dicots) which would kill the plant.
Why does the lower epidermis have more stomata than the upper epidermis of a leaf?
Plant undergoes a process called transpiration. Transpiration is the removal of water (vapour) from the upper
parts of the plant (stem, leaves). The opening and closing of stomata have huge influence on the rate of
transpiration. If the amount of stomata per unit area is more in the upper surface of the leaf then, more
transpiration occurs which might be detrimental for the plant. Since, the upper leaf blade is directly faced to
the sun, the rate of transpiration increases. Hence, to prevent excessive transpiration, stomata are more in
lower surface i.e. relatively less transpiration happens from the lower epidermis.
Plants also remove water in the form of (liquid), this is guttation. Stomata has no influence on this process.
Note:
1. Transpiration involves water vapour while guttation happens in the form of liquid (not water vapour).
2. Transpiration is a necessary evil i.e. needed for plant, but excessive is harmful.
3. Closing and opening of stomatal pore is due to two surrounding guard cells.
HOW DO PLANTS REPRODUCE
Asexual plant reproduction is seen from tuberous roots, stolons, rhizomes, stem tubers, corms, suckers, and bulb offsets
from either tunicate bulbs or scaly bulbs.
The potato, cyclamen and begonia are stem tubers. Potato tubers are a modified portion of the underground base of a
stem that is enlarged to store starch for future growth and has 'eyes' for future growth. When the potato sprouts new
stems, new plants, from the eyes on top of the tuber it also grows roots from the eyes on the lower side. Stems grow from
any eye whether in the middle of the tuber or at the ends so the larger the tuber & more numerous the tubers the plant
can produce in a growing season the more stems it will produce the next year.
Tulips are small plants that produce both flowers, for sexual reproduction, and bulb offsets as clones. (Offsets are small
bulbs that split off from the parent plant asexually.)
When tulip seeds germinate in sunny fertile locations they grow to maturity over several years then begin to produce bulb
offsets. The offsets mature to grow their own flowers. This eventually produces clusters of flowers for better chances of
attracting pollinators than just the flower from the first bulb. Large groups of flowers get pollinated more reliably to
increase the chances of reproductive success for each clone so greatly increase the parent plant's fitness.
Plants have reproductive organs most commonly seen in flowers. Flowers differ in the accessory structures they bear in
relation to the actual reproductive organs; the pistil & stamen. The entire purpose of a flower is to ensure reproduction,
fertilizing the egg by the pollen and producing a fruit that bears seed.
Since pollen is not motile most plants rely on wind, water, or animals to transport the pollen from one flower to another
flower's receptive stigma. Plants that rely on animals as pollinators are the ones with showy corollas and accessory parts
typically used in horticulture.
Monocots= M vs Dicots = D
Short and sweet!!!!!
M: Stems have scattered bundles in cross-section
M: Veins are parallel in the leaf
M: Flower parts in 3 or multiples of three
M: Seeds have one seed leaf in development
M. Roots are usually longer (deeper/tap like) and less branchy
D: Stems have a circular bundle arrangement in XS
D: Veins are netted in the leaf
D: Flower parts are in 4's and 5's or their multiples
D: Seeds have two seed leaves in development
D; Roots are usually more branchy and spread out.