Exam 4 Flashcards
characterizes unicellular organisms
protoplasmic grade
an aggregation of cells that are functionally differentiated
cellular grade
an aggregation of similar cells into definite patterns or layers and organized to perform a common function
tissue grade
an aggregation of tissues into organs
tissue-organ grade
organs work together to perform some function, producing the highest level of organization
organ-system grade
Any plane passing through center divides body into mirrored halves
spherical symmetry
Body can be divided into similar halves by more than 2 planes passing through the longitudinal axis.
radial symmetry
What are some characteristics of radial symmetry?
Organism has no anterior or posterior end and can interact with surroundings in all directions
A form of radial symmetry in which part of the organism is single or paired rather than radial
biradial symmetry
Organism can be divided along a single plane into two identical portions
bilateral symmetry
The differentiation of a head region with concentration of nervous tissue and sense organs
cephalization
What are some characteristics of bilateral symmetry?
Organisms are better suited for directional movement and they are associated with cephalization.
Water moves through cell walls
apoplast
Water moves from protoplast to protoplast via plasmodesmata
symplast
Water moves from protoplast to protoplast crossing plasma membranes
transcellular
How does the active transport of protons aid in the cotransport of molecules against their concentration or electrical gradient?
ATP activated proton pumps force more protons on one side of the membrane, creating a pH gradient. Molecules that fit the same cotransport enzyme can then bind at the same time as the protons and enter the cell
The movement of liquid in response to a pressure gradient
bulk flow
How does bulk flow differ from osmosis?
Unlike osmosis, bulk flow is independent of solute concentration.
The loss of water vapor from leaves and other aerial parts of the plant
transpiration
Transpiration creates a negative pressure that pulls water upwards from the roots
cohesion-tension hypothesis
How does transpiration affect leaf temperature?
Transpiration results in evaporative cooling, which can lower a leaf’s temperature. This prevents the leaf from reaching temperatures that could denature enzymes.
What are the basic steps involved in the opening and closing of stomata?
- Proton pump is activated
- K+ moves into guard cells
- Negative osmotic pressure pulls water into guard cells
- Turgid guard cells=open stomata
What morphological features limit transpirational water loss? How do they do this?
Leaves have stomata which can open and close due to guard cells. They also have a waxy cuticle which limits water loss on the parts of the leaf that don’t have stomata.
Describe essential elements concerning plants?
required to complete life cycle, part of an essential molecule, and there are 17 common to all plants
Describe beneficial elements?
essential for a limited number of species and involved in specialized pathways or symbioses
What symptoms would a phloem-mobile element deficient plant have? (This may not be a good question)
chlorosis, or yellowing of the leaves
What are some of the symbiotic relationships that help plants obtain mineral nutrients more efficiently?
root nodules and mycorrhizae
What modes of action are used by plant hormones to stimulate growth and development?
increasing cell elongation, increasing the rate of cell division, and/or influencing differentiation
What is the acid growth hypothesis?
Proton pumps activate expansins in the cell wall, polysaccharide cross-links are cleaved which loosens the cellulose, and ions move into the cell which decreases osmotic pressure so water follows to increase pressure potential
Explain the series of experiments that helped botanists understand the role of auxin in phototropism.
It was discovered that the tip of the stem is what senses light. Then, it was thought that the signal for phototropism was mobile, but that was proven wrong(?) Finally, a shoot tip was grown on an agar block so the chemical would diffuse into the agar block. The block would then stimulate growth. By placing blocks on only one side of the shoot tip, it was proven that growth is actually stimulated on the dark side and auxin pushes growth toward the sun.
What hormones are involved in maintaining dormancy or stimulating germination?
Absciscic acid maintains dormancy in buds and seeds, gibberellic acid stimulates germination.
What are the five grades of organization?
protoplasmic grade, cellular grade, cell-tissue grade, tissue-organ grade, organ system grade
Which type of symmetry is rarely found in animals?
spherical symmetry