Biological systems utilize free energy and molecular building blocks to grow, to reproduce, and to maintain dynamic homeostasis.
Enduring understanding 2.A: Growth, reproduction and maintenance of the organization of living systems require free energy and matter.
Living systems need to keep order, grow, and reproduce. According to the laws of thermodynamics, to offset entropy, energy input must exceed energy lost from and used by an organism metabolic rates, physiological changes, and variations in reproductive and offspring-raising strategies. The lack of energy can disrupt the ecosystem. Some organisms can capture, use, and store free energy. Cells whereas heterotrophs capture energy from carbon compounds produced by others. Photosynthesis traps free energy and is used to produce carbohydrates from CO2 and H2O. Cellular respiration and fermentation use free energy that are available from sugars and from interconnected, multistep pathways (glycolysis, the Krebs cycle, and the electron transport chain) to phosphorylate ADP, producing the most common energy carrier, ATP. The free energy available in sugars can be used to drive metabolic pathways vital to cell processes. Photosynthesis and cellular respiration are interdependent in their reactants and products. Organisms must exchange matter with the environment to grow, reproduce, and maintain organization. Water and nutrients are important for building new molecules.
ESSENTIAL KNOWLEDGE 2.A.1 : ALL LIVING SYSTEMS REQUIRE CONSTANT INPUT OF FREE ENERGY
Biologists recognize life by what living things do. Here are some of them:
-Order: Some organisms have organized structures.
-Growth and development
-Reproduction
-Regulation e.g. blood regulation
-Energy processing
-Respond to the environment
-Adapting
Diversity is the hallmark of life.
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Ecosystem: the sum of all organisms living within its boundaries and all the abiotic factors w/ they interact with.
Energy is conserved, but degraded to heat during ecosystem process.
-Order: Some organisms have organized structures.
-Growth and development
-Reproduction
-Regulation e.g. blood regulation
-Energy processing
-Respond to the environment
-Adapting
Diversity is the hallmark of life.
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Ecosystem: the sum of all organisms living within its boundaries and all the abiotic factors w/ they interact with.
Energy is conserved, but degraded to heat during ecosystem process.
Enduring understanding 2.C: Organisms use feedback mechanisms to regulate growth and reproduction, and to maintain dynamic homeostasis.
Organisms respond to changes in their internal and external environments through behavioral and physiological mechanisms. Organisms use negative feedback mechanisms to maintain their internal environments by returning the changing condition back to its target set point, while positive feedback mechanisms amplify responses.
Essential knowledge 2.C.2: Organisms respond to changes in their external environments.
a. Organisms respond to changes in their environment through behavioral and physiological mechanisms.
Taxis and kinesis in animals:
Taxis and kinesis in animals:
In changing locations, some animals rely on kinesis (a change in activity or turning rate in response to a stimulus). In contrast to a kinesis, a taxis is an orientated movement toward (positive taxis) or away from (negative taxis) some stimulus.
Enduring understanding 2.D. Growth and dynamic homeostasis of a biological system are influenced by changes in the system’s environment.
a. Cells activities are affected by the interactions with biotic and Abiotic factors.
-Temperature: It is an important factor in the distribution of organisms because of its effect on biological processes. Cells may rupture if the water temperature they contain freezes (below 0ºC), though extraordinary adaptations enable some organisms, such as therrmophilic prokaryotes to live outside the temperature range habitable by other life.
-Water availability: A dramatic variation in water availability among habitants is another important factor in species distribution. Species that living at the seashore or in tidal wetlands can desiccate as the tide moves away. Desert organisms, for example, exhibit a variety of adaptations acquiring and conserving water in dry environments.
-Sunlight: Sunlight is important because it provides energy to the photosynthetic organisms, and the lack of it can cause little distribution of these species. Too much light can also limit the survival of the organisms. The atmosphere is thinner at higher elevations, absorbing less ultraviolet radiation, so the sun’s rays are more likely to damage DNA and proteins.
b. Organism activities are affected by interactions with biotic and Abiotic factors.
- Salinity and pH: The salt concentration of water in the environment affects the water balance of organisms through osmosis.
-Water availability: A dramatic variation in water availability among habitants is another important factor in species distribution. Species that living at the seashore or in tidal wetlands can desiccate as the tide moves away. Desert organisms, for example, exhibit a variety of adaptations acquiring and conserving water in dry environments.
-Sunlight: Sunlight is important because it provides energy to the photosynthetic organisms, and the lack of it can cause little distribution of these species. Too much light can also limit the survival of the organisms. The atmosphere is thinner at higher elevations, absorbing less ultraviolet radiation, so the sun’s rays are more likely to damage DNA and proteins.
b. Organism activities are affected by interactions with biotic and Abiotic factors.
- Salinity and pH: The salt concentration of water in the environment affects the water balance of organisms through osmosis.
Essential knowledge 2.E.2: Timing and coordination of physiological events are regulated by multiple mechanisms.
b. In animals, internal and external signals regulate a variety of physiological responses that synchronize with environmental cycles and cues.
b. In animals, internal and external signals regulate a variety of physiological responses that synchronize with environmental cycles and cues.
Release and reaction to pheromones: Many animals use pheromones to communicate. They are common among mammals and insects, often related to reproductive behavior. They are the basis of chemical communication. Pheromones also functions in non-reproductive behaviors. They can be efficient at remarkable low concentrations.
Essential knowledge 2.E.3: Timing and coordination of behavior are regulated by various mechanisms and are important in natural selection.
a. Individuals can act on information and communicate it to others.
a. Individuals can act on information and communicate it to others.
Essential knowledge 2.A.3: Organisms must exchange matter with the environment to grow, reproduce and maintain organization.
3. Living systems depend on properties of water that result fromits polarity and hydrogen bonding.
3. Living systems depend on properties of water that result fromits polarity and hydrogen bonding.
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• Cohesion
• Adhesion • High specific heat capacity • Universal solvent supports reactions • Heat of vaporization • Heat of fusion • Water’s thermal conductivity |
Enduring understanding 2.B: Growth, reproduction
and dynamic homeostasis require that cells create and
maintain internal environments that are different from
their external environments.
and dynamic homeostasis require that cells create and
maintain internal environments that are different from
their external environments.
Cell membranes separate the internal environment of the cell from the
external environment. The specialized structure of the membrane described
in the fluid mosaic model allows the cell to be selectively permeable, with
dynamic homeostasis maintained by the constant movement of molecules
across the membrane. Passive transport does not require the input of
metabolic energy because spontaneous movement of molecules occurs
from high to low concentrations; examples of passive transport are osmosis,
diffusion, and facilitated diffusion. Active transport requires metabolic energy
and transport proteins to move molecules from low to high concentrations
across a membrane. Active transport establishes concentration gradients
vital for dynamic homeostasis, including sodium/potassium pumps in nerve
impulse conduction and proton gradients in electron transport chains in
photosynthesis and cellular respiration.
external environment. The specialized structure of the membrane described
in the fluid mosaic model allows the cell to be selectively permeable, with
dynamic homeostasis maintained by the constant movement of molecules
across the membrane. Passive transport does not require the input of
metabolic energy because spontaneous movement of molecules occurs
from high to low concentrations; examples of passive transport are osmosis,
diffusion, and facilitated diffusion. Active transport requires metabolic energy
and transport proteins to move molecules from low to high concentrations
across a membrane. Active transport establishes concentration gradients
vital for dynamic homeostasis, including sodium/potassium pumps in nerve
impulse conduction and proton gradients in electron transport chains in
photosynthesis and cellular respiration.
Essential knowledge 2.B.1: Cell membranes are selectively permeable due
to their structure.
to their structure.
Cell membranes separate the internal environment of the cell from the external environment.
The head is polar, so it's hydrophilic ("water loving"). The tails are non-polar, so they are hydrophobic ("water fearing"). The head tend to interact with water and therefore remain in contact with water, and the tails tend to huddle together with one another and exclude water. If enough phospholipids are thrown into water, they will spontaneously form a phospholipid bilayer (that will then ball up to form a sphere): that is the arrangement that minimizes the amount of contact between the hydrophobic tails and the water medium while at the same time maximizes the amount of contact between the hydrophilic heads and water