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In which group of plants did microphylls first appear?
clubmosses
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Does the sporophyte of the gametophyte better protect against harmful mutations?
sporophyte
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In which group of plants did stomata evolve first?
mosses
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Which of the following groups of plants lacks motile sperms?
1. horsetails
2. liverworts
3. gymnosperms
4. advanced algae
Gymnosperms
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What are the 2 major groups of angiosperms?
dicots and monocots
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what are the major defining features of monocots?
- fibrous root
- sheath leaf base
- parallel leaf venation
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what are the major defining features of dicots?
- tap roots
- petiole leaf base
- reticulate leaf venation
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What is the modular structure of stems?
- Structural unit of stem and root is called a phytomere
- In stem, one phytomere includes:
- 1. an internode
- 2. the leaf subtended at the upper end of the internode
- 3. the axillary bud in the axil of that leaf
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What can a section of the main root along with a subtended root branch be considered?
a phytomer or a structural root module
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What is unique about the angiosperm plant body unline animals?
- Has permanent embryonic regions or meristems
- The cells in these regions retain the capacity to divide throughout the life of the plant which may be thousands of years
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What are apical meristems?
- Indeterminate or permanent
- -shoot apical meristem (SAM)
- -root apical meristem (RAM)
- The activity of apical meristems results in primary growth and increase the length of the shoot-root axis and the height of the plant
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What is the lateral meristem?
- Indeterminate or permanent
- Cambium: produces xylem towards the inside and phloem towards the outside, increasing the diameter of the plant
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What are temporary meristems?
Produce organs with finite size, such as leaf and flower parts. They lose ther meristematic character when the organ reaches full size (leaf, flower, etc)
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Where are the permanent meristems located in higher plants?
- the terminal bud contains a shoot apical meristem
- in woody plants the vascular cambium and the cork cambium thicken the stem and root (lateral meristems)
- root apical meristem located on the root cap
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How can you tell the difference between simple and compound leaves?
- simple - single blade; means one stem has one big leaf (like a maple leaf)
- compound - consist of leaflets arranged along a central axis (like most plants)
- doubly compound - further division of the axis (like a fern frond)
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What are stipules?
- Little pointy things around leaf edge
- may be modified into tendrils or spines
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Which 2 structures of a leaf can be modified into tendrils?
- Stipules
- Terminal leaflets
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What is phyllotaxy?
patterns of leaf arrangement
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Describe spiral phyllotaxy
leaves grow from stem in spiral pattern all the way around
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Describe alternate phyllotaxy
alternate from side to side, leaves originate from their own spot
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Describe distichous phyllotaxy
leaves on opposite sides of stem, grow flat, leaves originate from same spot on stem
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Describe decussate phyllotaxy
in 3D space it is both alternate and distichous
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Describe whorled phyllotaxy
4 leaves on all 4 sides of stem in 3D space
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what is the shape of a monocot leaf?
consists of leaf sheath, leaf blade, and sometimes ligules and auricles
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how are vascular bundles arranged in a cross-section of the stem in dicots?
in a ring
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how are vascular bundles arranged in a cross-section of the stem in monocots?
scattered
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what is the cambial ring?
- In dicots, cambium of adjacent vascular bundles gets joined forming the cambial ring
- The cell division activity of the cambial ring forms secondary xylem towards the inside secondary phloem towards outside, constituting secondary growth
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What gives rise to concentric annual rings?
- Increase in dicot stem diameter by secondary growth
- Within an annual ring, cells formed during wet season are larger than cells formed during drier season. Thus an examination of annual rings in trees cross-sections can tell us abotu past climate
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What is cork cambium?
- A lateral meristem
- Sometimes produced in the outer part of the bark and gives rise to cork
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What is the periderm?
cork cambium and the tissues (cork and phelloderm) it produces are called periderm
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What is a lenticel?
The cork is suberized to a water-impermeable layer. However the underlying cell layers still need to breathe. Thus outer layer of the corky layer is disrupted and forms a lenticel.
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Memorize this picture for leaf structure and function:
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What is RAM?
- root apical meristem
- covered by root cap the cells of which continuously slough off
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How do cells in the root cap know which way to grow?
Cells at the center of the root cap sense gravity
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Is there any part of the root that is dormant?
Yes, a few cells at the center of RAM constitute the quiescent center
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Where are the cell growth centers in RAM?
There is a zone of cell division just behind the RAM followed by a zone of cell elongation which is followed y zone of cell maturation and specialization
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What is the purpose of root hair?
- Present in the zone of maturation
- increase the surface area for absorption
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Where do lateral branches arise from?
- Arise from pericycle, located deep inside the main root
- very difficult to break
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Where do shoot branches arise from?
- Arise from the cortex, superficial layer
- very easy to break
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Leaf modification - pitcher
- Leaf blade modified into a pitcher
- Makes carniverous plant
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What is the typical flower structure?
- Pentamerous (mostly dicot) and trimerous (mostly monocot) flowers (petals)
- Top part of the peduncle/stalk of the flower is called thalamus
- Stamen = filament + anther
- Carpel = ovary + style + stigma
- Flower may have one or several carpels fused together
- You can cut a cross-section of a fruit and see how many carpels it has
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All flower parts are modified _______.
Leaves
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Why is the stem radial in cross-section fortified by vascular system?
Radial symmetry is optimal in providing strength against lateral swaying stresses. It has bark/cork on outer surface to protect against pathogens
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Why are the plant roots underground?
- Not subjected to wind pressures
- Although radial in cross-section their mechanical strength is located along the center of the cylinder
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Why are leaves flat?
Intercepting maximum light for which a flat surface is optimal. Thus leaves are flat, bilaterally symmetrical with chlorophyll-containing cells concentrating on the upper part of the leaf interior
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Why do monocot leaves nearly vertical?
Have no distinction of upper and lower parts of the leaf. Both sides intercept light
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What are flower parts modified forms of?
Appropriately modified leaves to perform reproductive function
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