1.0 Most organisms are active in a limited temperature range
CNS in Homeostasis
- Acts as the control centre for all resposnes. - Coordinates all the resposnes. it recieves info, interprets it and initiates a resposne.
Main difference between endotherms and ectotherms in temperature regulation.
- Endotherms are able to regulate their core body temps via a feedback system - Ectotherms do not have this system and rely on structural and behvaiourial adaptations to control internal temperature.
Role of Enzymes in metabolism
- Enzymes are biological catalysts this means that they lower the energy required to start a chemical reaction within a cell but do not get used up by the reaction. - Through this they increase the rate of chemical reactions. - Without enzymes, metabolism would be to slow to support life.
Explain the specifcity of enzymes
- Enzymes are highly specific in their action; this means that each enzyme acts on one substrate only. - This is because the shape of the active site of the enzyme matches the shape of the substrate.
Examples of temp regulation in an Australian endotherm.
- In hot conditions, the red kangaroo licks the inside of its paws, where skin is thinner and blood supply is closer to the surface, so that heat can easily be dumped to the outside through the evaporation of saliva. - The large ears of the rabbit-cared bandicoot provide a large surface area to passs excess heat when it is burrowing during the heat or the day.
How do endotherms on land regulate body temps?
- Larger animals are common in colder climates as they have a low SA:V ratio meaning less area for heat loss. - Dilating blood vessels allows more bllood to come to the surface of the skin where it can be cooled. - Many animals allow water to evaporate fromt heir body to keep them cool. Humans release water from sweat glands however animals with fur find this ineficcent and instead use panting as an alternative. - Fur and feathers stand up when it is cold therefore trapping air and warming up the body with a layer of warm air. - Shivering increases metabolic rate and rapid vibration of the muscles produces heat which warms the body.
How do ectotherms on land regulate temps?
- Sunbaking - Shade and burrows - Nocturnal behaviour - Domant state during winter ( hibernation )
Example of temp regulation in an Australian Ectotherm.
- The netted dragon lies in the sun to absorb warmth to heat its body until the body temperature is around 36C. -It will then retreat to its burrow to stop becoming too hot.
Chemical Composition of Enzymes
- They are Globular proteins - These protiens consist of one or more polypeptide chains which are amino acids held together by peptide bonds.
Factors that affect enzyme activity
- pH - Temperature - Substrate concentration
Name the Two stages of Homeostasis.
1. Detecting changes from the stable state. 2. Counteracting changes from the stable state
Describe the first stage of homeostasis.
A receptor detects changes in the organisms internal environment. Sensory organs detects changes in the external environment. Any change or deviation that requires a response is considered a stimulus. Examples of external stimuli: Light, sound, temperature. Examples of internal stimuli: Levels of CO2, oxgyen levels, water. Examples of receptors: eyes and ears of mammals.
Describe the second stage of homeostasis.
After receptors detect changes, organisms can react by counteracting the change to ensure stable state is maintained. Effectors bring about responses to stimuli. Effectors can either be muscles or glands: muscles bring change by movement and glands bring about change by secreting chemical substances.
What can happen to plants at temperature extremes?
As many important enzymes are involved in photosynthesis and respiration and are embedded in plant membranes, extremes of temperature can be a major problem.
Peripheral nervous system in Homeostasis
Branching system of nerves that connects receptors and efectors. The system transmits messages from the central nervous system and back.
What the Nervous system consists of
Central nervous system and the peripheral nervous system.
Explain why the maintenance of a constant internal environment is important for optimal metabolic efficency
Enzymes are essential for proper metabolic function in an organism.Enzymes work optimally in an environment where their optimum temperature and pH conditions are met. At temperatures and pH values other than the optimum, the enzymes fail to work efficiently or to be kept as stable as possible. Therefore a constant stable environment is needed for metabolic efficency.
Homeostasis
Homeostasis is the process by which the internal environment is kept within normal limits regardless, of the external environmental conditions.
Identify some responses of plants to an overly hot environment.
Leaf orientation - in hot weather, leaves mayy be turned to have minimal exposure to the sun's rays as less radiant energy from the sun will fall on the leaf. Leaf fall - leaves are dropped in hot periods thus decreasing the surface area through which heat may be gained and water vapour lost through transpiration. Radiation - a plant radiates heat to objects in its environment.
The enzyme that breaks down Protein.
Pepsin found in stomach.
Characteristics of the peripheral nervous system
Sensory nerves and the effector nerves
Ambient Temperature
Temperature of the environment
Characteristics of the CNS
The brain and spinal cord
Identify the broad range over which life is found compared with the narrow limits for individual species.
The great majority of living organisms are found in the 0C to 45C range and for each individual species the range is even narrower. Below 0C, cells risk ice crystals forming in them and above 45C, proteins, such as enzymes, within cells may denature. Examples of species which can endure extreme temperature include thermoacidophiles which exist in temperatures around 120C. Each species is most comfortable at a temperature range which is narrower than the range for living organisms and this is due to the fact that its structural behavioural and physiological adaptations allow it to thrive in this range.
Use a simple model to describe their specificity on substrates
The lock and key model illustrates the action of an enzyme. This shows only one small part of the enzyme molecule being able to form a complex with the substrate. This is the active site. Only a specific substrate can bond in that site and this makes the enzyme specific to that substrate.
How do endotherms in water regulate body temps?
They have a layer of fat called blubber that acts as insulation preventing rapid heat loss. Also a the secretion of oils in birds and mammals insulates the skin from water and prevents heat loss.
Body processes that are controlled by homeostasis
This includes conditions such as temperature, pH, gas levels, water and salt concentrations.
How do ectotherms in water regulate temperatures?
Water temperatures change very little. Their metabolism is suitable for the temp of the surrounding water and since it remains relatively constant there is no need for adaptations to regulate body temp.
The role of nervous system in homeostasis.
When the environment exceeds a comfortable level for the body, sensory neurons conduct a nervous impulse to the hypthalamus found in the brain. Nerve impulses pass this information from the receptors to effector neurons then onto effectors, such as blood vessels, glands and muscles.
Identify some responses of plants to an overly cold environment.
in cold conditons extracellular ice formation causes dehydration. Some palnts can tolerate freezing temepratures as low as -50C by altering their solute concentrations and through the lack of ice-nucleating sites in cells to prevent intracellular freezing. Dormancy is a process in which plants lose elaves to avoid damage in cold conditions.
How is pH used as a way of describing the acidity of a substance
pH stands for Power of hydrogen. It is a scale related to the concentration of hydrogen ions in a solution. The scale is between 1 and 14, where 1 is more acidic and 14 is more alkaline.
