BIOL-1507EL Study Guide - Quiz Guide: Starch, Pericycle, Land Of Oz
27 Jun 2018
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BIOL-1507 - Lab 3 & 4 Quiz Review
Lab 3 - Leaves
-Land plants have developed a leaf structure that contains a watery “culture” of
chlorenchyma (cells with chloroplast) sandwiched between two protective layers, the
upper and lower epidermis
-The epidermis is porous and will allow passage of carbon dioxide and oxygen
A. The Mesomorphic Leaf
-These are plants that requires moderate amount of water regularly throughout
the growing season, they have leafs called mesomorphic leaves
-The majority of flowering plants are mesophytes
1. Upper epidermis
2. Mesophyll
1. Pallisade parenchyma (type of
chlorenchyma)
2. Spongy parenchyma
3. Vascular Bundles
1. Xylem
2. Phloem
3. Sclerenchyma (part of the sheath
cells)
4. Stomata
5. Guard cells
6. Lower epidermis
1. Eudicotyledon Leaf
-We examined the lilac (Syringa) leaf
-The upper epidermis is a layer of closely packed cells, and they are compact in order
to prevent excessive water loss and provide mechanical support
-These cells do not have chloroplast
-The outer walls of the cells are covered by a waxy noncellular layer called the cuticle
that also helps prevent water loss
-Mesophyll is compose of chlorenchyma, veins, a certain amount of fibrous tissue, and
free space
-Chlorenchyma is a tissue composed of thin-walled parenchyma cells containing
abundant chloroplasts
-The chlorenchyma in the upper part of the mesophyll is known as the palisade
parenchyma
-The lower part is called the spongy parenchyma
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-Specialized spores called stomata occur all over the lower epidermis and control
the passage of these gasses, there may sometimes be the odd stomata on the
upper epidermis
-Veins are cylindrical strands of vascular tissue and occur mainly in the mesophyll
-The xylem cells in the veins are easily recognized by their thick angular red
stained cell walls and absent of cell content.
-The xylem brings the water into the mesophyll
-Phloem cells are less distinct as they are thin walled, usually of small diameter,
and located below the xylem
-There are rings of large thin walled parenchyma cells that encircle the veins
-These are called the bundle sheath cells
-They are important because they are though to serve as flow channels
between veins and chlorenchyma
-The lower epidermis is similar to the upper epidermis, except that is have many
stomata that control the passage of gasses in and out of the cell
-Each stomata has two sausage shaped guard cells
- Changes in the shape of the guard cells are due to changes in its water content
-Stomata are open as a result of water pressure in the guard cells
-When light and temperature are high, the leaf can stabilize its temperature
somewhat by evaporating water from its mesophyll out through the stomata
The High Efficiency Leaf
-The monocotyledons most valuable to man are those known as the grasses, like
sugar cane, cereals, corn, wheat, rice, sorghum, etc
-These have evolved more efficient photosynthesis reactions, particularly those
trapping carbon dioxide
-This explains their extreme value as a food source
-They have:
-1) More compact mesophyll of the leaves to maximize conduction between
the cells and also minimizes the possibility of drying
-2) Numerous veins that provide each cell with more direct access to water
-3) Big sheath cells around the veins to actively accumulate starch in
specialized chloroplasts
-All of this adds up to higher rates of photosynthesis which results in greater
yield and more vigorous growth
-They also have large bubble like bulliform cells, that will lose water when water loss
from the leaf is high, in order to shrivel pup causing the leaf to roll up or fold up
-This reduces evaporation from those stomata on the leaf surface
now enclosed in the roll
B. The Xeromorphic Leaf
-The xeromorphic leaf is one that is designed so that its water
losses are minimized since they grow in dry places or in
desserts
-Other plants that live in the wet tropics also have xeromorphic
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leaves in order to adapt for survival when the annual dry
season occurs
-This leaf has furrows on the upper surface in which the
stomata occurs
-Abundant sclerenchyma is also present surrounding the
vascular bundles
-They also have very compact photosynthetic mesophyll
C. The Hydromorphic Leaf
-The hydromorphic leaf is one that is found in plants that
grow either submerged in water or with their roots
continually in wet soil and their leaves floating on
the surface of the water
Lab 4 - Young Stem and Root Structure
-The arrangement of tissues in the stem and root is in an efficient design that
integrates 5 different functions:
-Support
-Conduction
-Storage
-Photosynthesis (Stem only)
-Growth
A. Herbaceous Stems
1. Herbaceous Eudicotyledon Stems
-We examined the buttercup stem (Ranunculus
sp.)
i) Supportive Function of the Stem
-Support is achieved by:
-supportive tissue (collenchyma and
sclerenchyma cells)
-the arrangement of supportive and fibrous
Document Summary
Biol-1507 - lab 3 & 4 quiz review. Land plants have developed a leaf structure that contains a watery culture of chlorenchyma (cells with chloroplast) sandwiched between two protective layers, the upper and lower epidermis. The epidermis is porous and will allow passage of carbon dioxide and oxygen: the mesomorphic leaf. These are plants that requires moderate amount of water regularly throughout the growing season, they have leafs called mesomorphic leaves. The majority of owering plants are mesophytes: upper epidermis, mesophyll, pallisade parenchyma (type of chlorenchyma, spongy parenchyma, vascular bundles, xylem, phloem, sclerenchyma (part of the sheath cells, stomata, guard cells, lower epidermis, eudicotyledon leaf. The upper epidermis is a layer of closely packed cells, and they are compact in order to prevent excessive water loss and provide mechanical support. The outer walls of the cells are covered by a waxy noncellular layer called the cuticle that also helps prevent water loss.
