Bio 162: Midterm #1

Review the structure of the chloroplast and know where the light reaction and the Calvin cycle take place.

- chlorophyll picks up light molecules - CO2 diffuses into the chloroplast - light reaction- thykaloid - Calvin cycle- Stroma

In what two ways does photorespiration drain energy from the plant?

1)ATP is used for photorespiration 2) CO2 isn't fixed onto any organic compounds because oxygen has taken its place

Describe the difference between adaptation and acclimatization (acclimation).

Adaptation happens over several years through natural selection, whereas acclimatization occurs in response to an environmental stimulus. Acclimation is artificially induced

Define an adaptation (natural selection, survival, reproduction). How does the structure of a trait relate to its function? Provide specific examples.

Adaptation is a heritable trait that increases fitness in a given environment, evolves via natural selection

Define Fick's law, and describe how this relates to the structure of respiratory surfaces (e.g., tracheae, lungs, gills).

Ficks law of diffusion- states that the rate of diffusion of a gas depends on five parameters: 1. the solubility of gas in the aqueous film lining the gas exchange surface 2. the temperature 3. the surface area available for diffusion 4. the difference in partial pressures of the gas across the gas exchange surface 5. the thickness of the barrier to diffusion Rate of diffusion = k(A)((P2-P1)/D) - A is large, the respiratory surface in the human lungs is very large - D is small, the respiratory surface is very thin - partial pressure gradient of the gas across the surface is very large

Diagram all reactions of C4 and CAM photosynthesis shown in class. Pay particular attention to steps in which energy is consumed or fixation occurs.

C4- 1) PEP carboxylase fixes CO2 in mesophyll cells 2) 4 carbon organic acid results and travels to bundle sheath cells 3) four carbon organic acids release a CO2 molecule that rubisco uses as a substrate to form 3-phosphoglycerate, which initiates calvin cycle

Define erythrocytes, leukocytes, and platelets, and describe their functions.

Erythrocytes- transport oxygen from the lungs to tissues throughout the body; play a role in transporting CO2 from tissues to lungs (99.9% of the formed elements) Leukocytes- part of the immune system; they fight infections Platelets- cell fragments that act to minimize blood loss from ruptured blood vessels; do so by releasing material that helps form the blockages known as clots

What happens to the sugar that is produced by photosynthesis? (storage, respiration, structure, cellulose)

The most important reaction sequence is the usage of G3P to produce the monosaccharide glucose (gluconeogenesis). Glucose is combined with fructose to form the disaccharide, sucrose. Sucrose is typically made when photosynthesis is occurring slowly; it is transported to other parts of the plant. (cytosol) When sucrose is abundant, glucose molecules are polymerized to form starch, which is stored in the cells. (chloroplast)

Marine bony fishes osmoregulation

Fish are losing water. so they drink ocean water and pump out salt. The fishes balance water loss by drinking seawater and actively transporting chloride ions out through their skin and gills. They have to use a sodium pump to get rid of excess salt (takes a lot of energy) They can also only afford to produce a very small volume of urine. Drinking sea water brings a large quantity of salt into the blood and this has to be removed. To replace the water they lose, saltwater fish drink sea water. To produce a small a volume of urine they must have a low rate of filtration of water into the kidney tubules. This is done by having a kidney with relatively few small glomeruli.

summarize the reactions occurring in the three phases of the Calvin cycle (fixation, reduction, regeneration). Where does the energy for these reactions? (RuBP, CO2, 3-phosphoglycerate, glyceraldehydes-3-phosphate (G3P))

Fixation-CO2 reacts with rubisco, creates 2 3 carbon molecules Reduction- 3PGA phosphorylated by ATP and reduced by e- from NADPH, makes G3P- some of this goes to make glucose and fructose (1 g3p molecule) Regeneration-rest of 5 g3p regenerate rubisco which is used for fixation again

Describe the interior of a typical leaf. How do gasses move from the atmosphere to the interior of the leaf?

Gases move first into the stomata (when open). They then move into air space where they are then put into mesophyll cells for photosynthesis. PEP carboxylase is concentrated in mesophyll cells and rubisco is found in bundle sheath cells.

Give examples of how some structures are modified into a shape that alters surface area to volume ratio.

Gills of a fish: smaller structures that give the fish more surface area to volume ratio so it is easier for the fish to exchange oxygen and CO2.

Marine sharks and cartilaginous fishes osmoregulation

In contrast, sharks are osmoconformers and ion regulators. Their body fluids are almost the same concentration of ions as seawater, but they use different ions. Sharks do have to deal with a slight influx of salt, which is excreted by a rectal gland. Concentrations of urea and trimethylamine oxide (TMAO) in body fluids leads to an osmolarity slightly higher than seawater. 1. sharks pump salt into their blood stream, when na diffused back through it co transports K and Cl and the cl and na then diffuse out of the fish and the potassium goes back into the blood

Does the surface area to volume ratio impose more of a limit on the upper body size of plants or animals? Why?

It imposes more of a limit on the upper body size of animals because they are alive and require much larger amounts of energy to keep their bodies functioning as well as allow for movement, whereas plants are mainly composed of dead tissues so they don't require as much energy and are stationary.

5. Articulate the important concept illustrated in figure 34.7

Leaf shape/arrangement is generally genetically determined. Sun leaves are thicker with smaller surface areas (to reduce water loss), while shade leaves are thin and broad with a high surface area. Phenotypic plasticity is more important (1) in environments where conditions vary because it gives individuals the ability to change the growth pattern of their roots, shoots, and stems to access sunlight, water, and other nutrients as the environment changes; and (2) in long-lived species because it gives individuals a mechanism to change their growth pattern as the environment changes throughout their lifetime.

What is the primary function of leaves? What other functions can modified leaves serve?

Leaves give plants a high surface area/volume ratio; therefore a plant with a lot of leaves and/or broad leaves will tend to lose water more quickly. A leaf is an appendage that projects from the stem laterally; function as photosynthetic organs. Leaves are produced in regions that are exposed to the highest levels of light to maximize its chances of capturing light.

Describe how mammals maintain homeostasis of body temperature (set point, sensor, integrator, effector, hypothalamus). Now apply this to a lizard. What about plants?

Mammals maintain their body temperature by sensing a change in core temperature outside of an accepted range called the set point, sending this information to the hypothalamus (integrator) to evaluate this information and decide what changes need to be made to fix it, and then a signal is sent to the effector which makes the appropriate changes to the body to return the body's temperature to the set point.

What properties of meristem cells permit plants to grow continuously (i.e. indeterminate growth) throughout life?

Meristem cells are populations of undifferentiated cells that retain the ability to undergo mitosis. Apical meristems are located at the tip of each root and shoot; they extend the plant body outward. Primary growth (increasing the length of the root and shoot system) is, therefore, possible.

Distinguish between positive pressure and negative pressure and explain how either of these two pressures can result in the movement of water. (guttation, cohesion-tension theory)

Positive Pressure (push to force water up)-as water flows into xylem from other root cells it forces fluid up the xylem -enough water can move to force water droplets out of the leaves--guttation Negative Pressure( Pull force)-creating low pressure at the top Cohesion-Tension Theory: negative force generated at air-water interface is transmitted through the water outside of the leaf cells----water in xylem goes into water in vascular tissues into roots and then water into soil --continuous transmission of pulling force possible 1. water present throughout plant 2. water is hydrogen bonded to one another in a continuous fashion

Distinguish between primary growth and secondary growth in plants.

Primary Growth (dermal, ground, vascular)-vertical growth (increases length of roots/shoots-cells derived from apical meristems FUNCTION: increase plants ability to absorb photons, acquire CO2, H2O and ions Secondary Growth (cork, secondary phloem, secondary xylem) (no dermal tissue)-increases width FUNCTION: increase amount of conducting tissue available and provide structural support required for extensive growth

Under what environmental conditions might there be selective pressure to promote branching? Inhibit branching?

Promote Branching-environments of open areas where there is a lot of sunlight and no competition Inhibit Branching-there is high competition for sunlight because the plant has to focus on certain branches getting tall in order to compete for sunlight

Under what environmental conditions might there be selective pressure to promote internode elongation? Inhibit internode elongation?

Promote internode elongation--in an environment where trees are close to one another and light competition is intense (trees taller, internodes longer) Inhibit internode elongation--promoted in environments where there is no competition for light (shorter trees, shorter internodes)

No two organisms look exactly alike. Distinguish the roles of morphological diversity and phenotypic plasticity in creating the differences between organisms.

Phenotypic Plasticity- changes in form or function due to the environment Genetic (Morphological) Diversity- differences in genes Morphological Diversity- morphological variation in the shoot system allows: - plants of different species to harvest light at different locations, minimizing competition - plants to thrive in a wide array of habitats

Compare and contrast the extent of phenotypic plasticity typically seen in animals and plants.

Phenotypic plasticity can give rise to new traits due to environmental conditions in plants and animals, but it can't completely change one animal or plant into a completely different animal or plant.

Trees can be killed if a ring of bark and vascular cambium all the way around the trunk are removed (this is called "girdling"). Explain why.*

Phloem is part of trees' method of transportation and sugars can't be transported between shoots and roots -if no phloem... roots will starve (HIGH sugar concentration in the phloem) .1. no way for sugars to be transported 2. cutting cambium-containing xylem and phloem means eventually tree cannot receive water and nutrients

Identify the three main types of nitrogenous wastes produced by animals, and give examples of an animal that produce each type.*

Urea- enzyme-catalyzed reactions convert ammonia to a much less toxic compound called urea (in mammals and adult amphibians) Uric acid- ammonia is converted to a white, paste-like substance that you have probably seen in bird feces; much less soluble in water (birds and other reptiles) Ammonia diffusion across gills into the surrounding water along its concentration gradient (freshwater and marine bony fishes)

Vascular Tissue System

Xylem- complex tissue consisting of tracheids, vessel elements, and frequently parenchyma cells and fibers (tracheids, vessel elements, and fibers are dead at maturity; primary and secondary cell walls); responsible for the transport of water and nutrients, structural support Phloem- complex tissue consisting of sieve tube elements, companion cells, and frequently fibers (fibers are dead at maturity); responsible for transport of sugars, amino acids, hormones, etc.

Compare the anatomy of xylem (vessel elements, pits) and phloem (sieve tubes, cytoplasm, plates).

Xylem--conducts water and dissolved ions from the root system to the shoot system vessel-elements- dead; short,wide; have perforations tracheids-pits (hole in primary and secondary cell wall); dead Phloem-- conducts sugar, amino acid, chemical signals and other substances throughout the plant body -sieve-tube elements -alive at maturity; long, thin, cells that have perforated ends (sieve plates); lack nuclei -companion cells- provide materials to maintain the cytoplasm and plasma membrane of sieve-tube members; function at sieve-tube elements "support staff"

What is the relationship between solute concentration and water potentials?What is the relationship between turgor pressure and water potential?

[solute] is inverse to water potential- as solute concentration increases water potential decreases as solute concentration increases, the solute potential decreases as pressure decreases (cell wall expands) water potential decreases as well, allowing water to flow in easier

Describe how the insect tracheal system delivers oxygen through the body.

air moves from the atmosphere into the spiracles and then through the tracheae to the tissues in the insect's body tracheae are alternately compressed and dilated as the muscles around them contract and relax. the muscle contractions and relaxations produce pressure changes that alter the volume of the tracheal system - volume of the tracheal system increases when muscles relax - volume of the tracheal system decreases when muscles contract, pressure inside the system increases, and gas moves out of the tracheae into the atmosphere

Identify the costs and benefits of each type of nitrogenous waste, focusing on the trade-off between production of uric acid and urea.*

ammonia - one nitrogen per molecule; highly toxic; requires lots of water to flush. in urine and diffuses across gills urea - two nitrogens per molecule; less toxic; requires less water to flush. in urine (mammals and gills (sharks) uric acid - four nitrogens per molecule; non-toxic; requires very little water to flush, with feces

State a hypothesis to explain why giant insects existed 300 million years ago, but could not possibly exist today.

atmospheric oxygen concentration was much higher than it is today. during the latter part of the Paleozoic era, the difference in partial pressure was increased, which may have increased the rate of diffusion of oxygen across the respiratory surfaces in insects

What are the advantages and disadvantages to a plant of OPENING stomata? And of CLOSING stomata?

closed- water stays in plant, but O2 build up and photorespiration occurs open- CO2 enters the plant, but water loss occurs

Interpret the oxygen-hemoglobin dissociation curve, and identify the situations in which the curve would be shifted to the left or right.

curve shifted left- people in high altitude. curve shift right-when tissues are exercising and need more o2 sigmoidal pattern occurs because the binding of each successive oxygen molecule to a subunit of the hemoglobin molecule causes a conformational change in the protein that makes the remaining subunits much more likely to bind oxygen

What is the primary function of roots? What other functions can modified roots serve?

roots transfer water, ions and nutrients throughout the plant, and store materials in the shoot for later use Modified Roots- can do more than just specialized function -adventitious roots- develop from shoot system not roots -pneumatophores- allow gas exchange between roots and atmosphere -storage roots- storage of carbohydrates and other nutrients for future use

Consider water as it moves from soil to root to stem to leaf to air. How does the water potential in these different regions compare? (xylem)

soil: water fills crevices between soil particles (solute driven), relatively few solutes, not under much pressure, water potential tends to be higher (relative to water in plant's roots) roots: high in solutes (solute driven), under considerable turgor pressure, water potential is less than water potential in soil air: water potential extremely low relative to the moist interior of a leaf water potential starts high (soil) goes to low (air) -plants gain water from soil and lose it in atmosphere

What is the primary function of shoots? What other functions can modified shoots serve?

stems- vertical aboveground structures node- where leave is attached, next to internode (segments in between nodes) axillary buds- nodes where leaves are attached to the stem; can turn into a branch, a horizontal extension of the shoot system apical bud- the tip of each stem and branch, where growth occurs that can extend the length - shoot system works to grow in directions that maximize chance of capturing light Modified Shoots- water storage; asexual reproduction (stolons and rhizomes- stems that grow horizontally); carbohydrate-storage organs (tubers); thorns for protection

The light reaction of photosynthesis begins when pigments in the chloroplast absorb light energy (photons). At the end of the light reaction, where is the energy derived from the photons stored?

stored as ATP and NADPH for use in the dark reaction

Compare and contrast the osmoregulatory challenges of living in the ocean, in freshwater, and on land.

the relative concentrations of water and solutes must be maintained within narrow limits, despite variations in the animal's external environment. An organism maintains a physiological favorable environment by osmoregulation (process by which organisms control the concentration of water and solutes in their bodies) regulating solute balance and the gain and loss of water and excretion, the removal of nitrogen-containing waste products of metabolism Living in the ocean= too many solutes On land= not enough water Fresh water= too much water

C4 and CAM photosynthesis are described as "CO2 pumps." How do these forms of photosynthesis differ from C3 and why should they be characterized as "pumps?

they are different from C3 plants because they utilize CO2 when needed, and minimize photorespiration when stomata are closed. They are "pumps" because they can control their use of CO2

Describe the structural and functional relationship between the respiratory and circulatory systems.

they are interconnected and the circulatory system picks up and circulates the gas exchanged in the respiratory system

Predict the relative success of C3, C4 and CAM plant in a cool, wet environment and in a hot dry environment.

C3- will survive and thrive in wet environment C4- survive and thrive in wet environment might be over hydrated CAM- overhydrated in wet environment

In C4 and CAM plants rubisco always operates under conditions of elevated CO2. How is this achieved?

C4 plants have PEP carboxylase which allows CO2 to be taken up into the plant very quickly, which allows stomata to open less CAM plants do C4 cycle during night and store it as acid and perform calvin cycle during the day so they don't have to open stomata

What is the role of hydrogen bonds in water movement from roots to leaves? (Cohesion-tension theory).

-water is pulled to the tops of trees along a water potential gradient via forces generated by transpiration at leaf surfaces 1. spaces in the middle of the leaf-- fill with moist air due to evaporation from the surfaces of the surrounding cells (water diffuses from inside of the leaf to the atmosphere) 2. water leaves leaf-- humidity of the spaces inside the leaf drops causing water to evaporate 3. tension pulls water that surrounds nearby cells out of the xylem 4. tension from water in leaf pulls water through the stem all the way from the root xylem by cohesion (continuous H-bonding) ----water molecules pulled up because the tension at the surface is much greater than H-bonding that pulls molecules to the side or down 5. Tension pulls water from root cortex cells--root xylem 6. Tension pulls water from soil into roots

How is water potential of the phloem different in the source and the sink? Draw a diagram showing how pressure and sucrose concentration influence water potential.

-water potential of the phloem in the source is high; sinks have a low water potential FLOWS FROM SOURCE TO SINK -water from the xylem flows into the phloem when there is a high concentration of sugar near the source -creates a high pressure near the source -high pressure drives sugar down from source to sink -water leaves phloem back into xylem when the sugar is actively pumped out

Sucrose becomes concentrated in the sieve tube elements in source tissue. Explain how this occurs and include the following in your description: companion cell, H+-ATPase, pump, cotransport*

1. Sucrose enters companion cells along with protons 2. Membrane protein in companion cells hydrolyzes ATP and uses the energy release to transport H+ across the membrane to the exterior of the cell 3. Increase proton pump or H+-ATPases; establish large differences in charge and proton concentration on the two sides of the membrane -electrochemical gradient favors entry of protons into the cell -co-transporter- protons and sucrose enter the cell together; protons along electrochemical gradient; sucrose against its concentration gradient

Diagram the mechanisms of NaCl excretion in the shark rectal gland and of reabsorption in the human proximal tubule (use terms: osmosis, concentration gradient, facilitated diffusion, primary active transport, secondary active transport).

1. sodium potassium pump pumps sodium ions out of epithelial cells across the basolateral surface, into the extracellular fluid (near blood) creating a gradient that makes sodium diffuse into the cell from the body 2. sodium moves from the extracellular fluid back down the gradient it just made, co transporting K+ and cl- 3. as cl- builds inside the cell it diffuse down its gradient out to the salt water 4. Sodium also builds up inside the cell and then leaves through the spaces in between cells 5. potassium goes back into the extra cellular fluid sharks have to create tmao to contract the urea that stays in their blood.

Identify the major parts of the mammalian nephron and list the substances reabsorbed at each part.*

1. the renal corpuscle filters blood, forming a filtrate or pre-urine consisting of ions, nutrients, wastes, and water 2. the proximal tubule has epithelial cells that reabsorb nutrients, ions, and water from the filtrate in the blood 3. The loop of Henle establishes a strong osmotic gradient in the interstitial fluid surrounding the loop; osmolarity of the fluid increases as the loop descends into the medulla 4. The distal tubule reabsorbs ions and water in a regulated manner- one that helps maintain water and electrolyte balance according to the body's needs 5. the collecting duct may reabsorb more water to maintain homeostasis

Define a fitness trade-off. Work through and be able to interpret the experiment on cricket trade-offs.

A fitness trade off is when a trait is adapted in order to improve one thing, but because of this something else won't work as well. The experiment proved that crickets have an energy trade off between reproductive and immune function. When the cricket was forced to constantly make new spermatophores, its immune function went down because it used up more energy for reproduction. On the other hand, when the cricket was injected with bacteria it had to fight off this infection and therefore has a smaller mass of gelatinous mass in its spermatophore (less reproductive success) because it used up more energy for immune function.

Identify the number of atria and ventricle in the hearts of the major vertebrate groups, and describe the functional consequences of differences in number of chambers.*

Amphibians, turtles, lizards, and snakes have paired atria with only partially separated pulmonary and systemic circulations; blood in the left and right atria may mix in the common ventricle before being expelled from the heart to the lungs or to the body. Turtles, lizards, and snakes have a bypass vessel running from the right side of the ventricle directly to the systemic circulation; also observed in the four-chambered hearts of crocodilians - these bypass vessels shunt blood from the pulmonary to the systemic circulation when the animal is underwater and not breathing, resulting in a great reduction in blood flow to the lungs Birds and mammals have fully divided ventricles and lack a bypass vessel; this configuration completely separates the pulmonary and systemic circuits. This causes highly oxygenated blood returned from the lungs to be ejected exclusively into the systemic circuit

Explain the relationship between these terms: apical meristem, axillary meristem, branching.

Apical meristem- located at the tip of each root and shoot; extend the plant body outward through division and differentiation of these cells. Axillary meristem- maintain their meristemic properties and remain undifferentiated; growth results in nodes that lengthen the plant horizontally (branching)

Compare apoplastic, transmembrane, and symplastic transport of water. Explain how the casparian strip of the endodermis promotes "filtering" of water that reaches the vascular tissue. (suberin, plasma membrane, plasmodesmata)*

Apoplastic: cell walls, which are porous and spaces that exist between cells (outside the plasma membranes) Symplast: continuous connection through cells that exists via plasmodesmata (inside the plasma membranes) Transmembrane: based on flow through aquaporin proteins Casparian strip: narrow band of wax secreted by endodermal cells, composed of suberin (forms a waterproof barrier where endodermal cells contact each other) -temporarily blocks apoplastic pathway by preventing water from creeping around the walls of endodermal cells and going into vascular tissue -for water and solutes to reach vascular tissue--have to cross membrane of an endodermal cell (acts as a filter)

Describe the major types of blood vessels.

Arteries- tough, thick-walled vessels that take blood away from the heart; small arteries are called arterioles Capillaries- vessels whose walls are just one cell thick, allowing exchange of gases and other molecules between blood and tissues; networks of capillaries are called capillary beds Veins- thin-walled vessels that return blood to the heart; small veins are called venules

Describe how water potential of a cell would change in the following conditions: -the cell wall is degraded by enzymes. -a pump transports Na+ out of the cytoplasm into the surrounding solution

As the cell wall is degraded by enzymes, water potential decreases If a pump transports sodium out of the cytoplasm into the surrounding solution, water potential increases

Compare and contrast endothermy and ectothermy, homeothermy and poikilothermy. Are endotherms most commonly homeotherms or poikilotherms? What physiological mechanisms do they use to achieve this?

Endothermy means that the organism is able to produce its own heat to meet its needs, while ectothermy means that the organism must get its heat from other sources. Homeotherms are able to maintain a constant internal body temperature, while poikilotherms allow their body temperature to rise or fall to fit the circumstance. Endotherms are most commonly homeotherms and they use metabolism to heat their body.

Dermal Tissue System

Epidermis- complex tissue consisting of epidermal cells, guard cells, trichomes, and root hairs Trichomes- hairlike appendages made up of specialized epidermal cells; may keep the leaf surface cool by reflecting sunlight, reduce water loss by forming a dense mat that limits transpiration, provide barbs or store toxic compounds that thwart herbivores, and trap/digest insects Shoots: protection and gas exchange Roots: protection; water and nutrient absorption

Identify the major tissue types in animals, and describe how their structure relates to their function.

Epithelial: lines body surface Connective: support; cells that secrete their own ECM Nervous: communication; neurons and support cells (glia) Muscle: movement Nervous and muscle cells only in animals!

Distinguish between heartwood and sapwood in terms of structure, function, and time of production.

Heartwood (dead) 1. inner xylem region 2. structural support but no longer transports water 3. comes before sapwood Sapwood (living) 1. outer xylem 2. active water-conducting xylem tissue

In a typical tree where are the living cells and where are the dead cells? Make a guess about how much of the bulk of the tree is alive vs. dead cells.

In a typical tree, the living cells are in the secondary growth of the tree (i.e. the most recent layer of xylem and phloem). This layer is called the "vascular cambium" and is responsible for moving water and nutrients throughout the plant. The dead cells are in the old layer of xylem (the wood of the tree) and also the outer layer of phloem, which is crushed and integrated into cork. Most of the tree is dead! Many cells are dead after functional maturity (after cells have differentiated and assumed normal function).

Diagram a stem and label the nodes and internodes. What structures make up a node?

Nodes- leaf and axillary meristem, together Internodes- portion of the plant stem in between nodes

Differentiate between osmoconformers and osmoregulators.

Osmoconformers are marine organisms that maintain an internal environment that is isosmotic to their external environment An osmoregulator is an organism that can regulate or keep the solutes or salts of its body fluid at a higher or lower concentration than the concentration of solutes in the external

Define the terms osmolarity (compare with water potential), hyperosmotic, hyposmotic, and isosmotic.

Osmolarity- concentration of solutes in solution Low osmolarity= little solute, high=lots of solute Free water= when water is not bound to anything, when ions are dissolved in solution the water is bound to them and cannot move A solution will have a lower and hence more negative water potential than that of pure water. Hyperosmotic- the solution outside the body has a higher solute concentration than the solution inside; water flows outside the body Hyposmotic- solution with a lesser concentration of solute ( fresh water compared to salt water). If a cell from a freshwater fish is placed into a beaker of salt water, the cell is said to be hypoosmotic to the water.

Identify the reasons why water and electrolyte homeostasis are important in animals.

Overhydration: cell swelling (hypotonic hydration) can cause cells to burst Dehydration : cells shrivel

Ground Tissue System

Parenchyma- simple tissue consisting of parenchyma cells (primary cell wall only); synthesis and storage of sugars and other compounds Collenchyma- simple tissue consisting of collenchyma cells (primary cell wall only; flexible cell walls); support, mostly in stems and leaves Sclerenchyma- simple tissue consisting of sclerenchyma cells: sclereids (protection, mostly in hard outer surfaces of seeds and fruit) or fibers (primary and secondary cell walls; dead at maturity; responsible for support)

Suggest an explanation for why phloem transport requires living cytoplasm in the sieve tube members (remember that xylem cells are dead at functional maturity.)

Represents a continuous system for transporting sugar throughout the plant body - sucrose enters the companion cells along with protons-hydrolyze ATP and use energy released to pump H+ across the membrane to the exterior of the cell -phloem is not dead at functional maturity; they have cell contents in which to carry things they transport

Why do the sieve elements of the phloem require companion cells? Why DON'T the tracheids and vessel elements of the xylem require companion cells? (Note: these cell types will be covered in more detail later.)*

Sieve elements-long, thin cells that have perforated ends (sieve plates)-responsible for transporting sugars and other nutrients -lack nuclei/chloroplasts/ most other major organelles Companion cells-contain all of the organelles normally found in a plant cell -companion cells are not conducting cells that provide materials to maintain the cytoplasm and plasma membrane of sieve-tube members, load and unload carbohydrates and other nutrients from the solution inside sieve-tube members Tracheids-in all vascular plants, water-conducting cells, long and slender with tapered ends, pits (gap in primary and secondary cell wall) Vessel Elements-shorter/wider, angiosperms, conducting cells with perforations (opening that lacks primary cell wall, still has secondary cell wall) -tracheids and vessel elements are DEAD at maturity and interact with fluids they conduct instead of the cytoplasm-don't need companion cells to maintain a cytoplasm or plasma membrane

For each type of transport across plasma membranes (simple diffusion, facilitated diffusion, primary active transport, and secondary active transport), describe how and why a molecule moves across a membrane.

Simple diffusion, down gradient Small nonpolar molecules just move through the membrane Facilitated diffusion, down gradient Channel (pore) that allows the passing of particular ions Carrier, also uses no atp but has a conformational change to allow the passing of ions Primary active transport, up gradient Pump uses ATP to transport molecules against their gradients Secondary active transport (cotransport)- relies on an electrochemical gradient established by a pump during primary active transport Symporter: a cotransporter that moves different solutes in the same direction Antiporter: a cotransporter that moves different solutes in opposite directions

Distinguish between sources and sinks. Make a list of plant tissues that are sources or sinks (photosynthesis, storage, respiration)

Sources: any tissue, site, or location where a substance is produced or enters circulation Sink: any tissue, site, or location where an element or a molecule is consumed or taken out of circulation -During growing season:-mature leaves/stems that are actively photosynthesizing and producing sugar (sources), moves to sinks [sugar use is HIGH and production is LOW] -apical meristem, lateral meristem, developing leaves, flowers, developing seeds and fruits, storage cells in roots -Early in growing season:-storage cells in roots act as sources and developing leaves act as sinks

Define homeostasis.

Stability in the chemical and physical conditions within an animal's cells, tissues, and organs.

Describe the roles of aldosterone and antidiuretic hormone in the formation of concentrated urine in mammals.

The hypothalamus monitors the amount of water in the body by sensing the concentration of electrolytes in the blood; a high concentration of electrolytes means that the level of water in the body is low. Antidiuretic hormone (ADH), produced by the hypothalamus and released by the posterior pituitary, causes more water to be retained by the kidneys when water levels in the body are low. ADH effects water retention by creating special channels for water, called aquaporins, inside the kidneys so that more water can be resorbed before it is excreted. Aldosterone, leads to the activation of sodium-potassium pumps and reabsorption of Na+ in the distal tubule, water follows by osmosis

Explain how size and surface area to volume ratio affect physiological processes.

The larger the organism, the smaller the surface area to volume ratio they have, meaning that it requires less effort per gram to perform bodily functions. The rate at which molecules and ions diffuse depends on the surface area available for diffusion; the rate at which nutrients are used and heat and waste products are produced depends on the volume of the animal Mass specific metabolic rate= total metabolic rate/mass - As an organisms size increases, its mass-specific metabolic rate must decrease

7. Leaves have a higher SA/V (surface-area-to-volume) ratio than other structures in the plant. What are the benefits and costs to the plants? (water, photosynthesis, gas exchange)

With a higher SA/V ratio, plants lose water more rapidly, but are also able to undergo photosynthesis more rapidly because they acquire more light (i.e. able to undergo light reactions more efficiently).

How does the current atmosphere differ from that in which photosynthesis evolved? (O2, CO2) How does the current Earth atmosphere reduce the efficiency of rubisco? (photorespriation)

When photosynthesis first evolved, there was more CO2 and less oxygen in the atmosphere. Having more oxygen in the atmosphere reduces the efficiency of rubisco because O2 and CO2 compete for the active site of rubisco. When O2 reaches the active site of rubisco, photorespiration occurs

Make a table to summarize the general structure and function of meristematic cells, parenchyma cells, collenchyma cells, and sclerenchyma cells. (cell division, differentiation)*

meristematic cells-undifferentiated cells (go on to become specialized cells)-undergo cell division in meristem-small/similarly look cells parenchyma cells-usually spherical or oblong, only primary cell walls, store starch deposits and basic metabolic cell functions, universal cell type, living collenchyma cells-elongated cells, primary cell walls (plastic), function mainly in support, even when mature their cell walls hold the ability to stretch and elongate, living sclerenchyma cells-specialized support cells that produce a thick secondary cell wall in addition to a thick primary cell wall, secondary cell wall has lignin, non-expandable secondary cell wall, support stems and other structures after active growth -usually dead at maturity (NO CYTOPLASM)-protection

Distinguish between open and closed circulatory systems, and name the animal groups that have each.*

open system is where the molymph (liquid) in vessels while the hemolymph (nutrients and waste transport) is in direct contact with tissues.(clams) a closed system is a continuous circut under pressure (human)

Describe how oxygen and carbon dioxide are carried in the blood.

oxygen binds to hemoglobin molecules in red blood cells while carbon dioxide combines with water to be transported as bicarbonate ion

Freshwater fish osmoregulation

they're losing salt. Many freshwater animals, maintain water balance by excreting large amounts of very dilute urine, and regaining lost salts in food and by active uptake of salts from their surroundings. Freshwater fish are the opposite. Water constantly moves into their bodies from the water so their kidneys excrete lots and lots of water and their gills do also. But, critically, they manage to hang on to salt to keep their blood at the right salinity. they have lots of glomeruli and filter their blood a lot helping them hold onto salt These fish must produce a very large volume of urine to balance this large intake of water. This large volume of urine carries salt with it, and the salt has to be replaced. Salt replacement is solved by chloride secretory cells in the gills, which actively transport salts from the surrounding water into the blood. they have sodium channels on their apical sides of their gill cells and can pull in salt

Recite the flow of blood through the human heart in the proper order.*

vena cava-RA-tricuspid valve-RV-pulmonary arteries-lungs-pulmonary veins-LA-bicuspid valve-LV-aorta

Water flows from one cell into another. How do the water potentials of these two cells differ?

water potential moves from high to low; water from one cell with a high water potential moves to another cell with a low water potential

Explain the relationship between wilting and turgor pressure.

wilting: an entire tissue loses turgor turgor: cells that are firm and that experience wall pressure when cells in a leaf or stem lose water to the atmosphere faster than it can be replaced, then the plasma membrane contracts and the cells shrivel --if cells do not regain turgor-- risk for dehydration-- wilting