Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
27 Cards in this Set
- Front
- Back
|
Why do organisms need to respond to their environment? |
To increase their chance of survival |
|
|
Define Homeostasis |
The maintaining of a stable internal environment |
|
|
Define a) Stimulus b) Receptor c) Effector |
a) A change in the internal or external environment b) They are specific to stimuli - they detect a change and communicate with effectors by the hormonal or nervous system c) Cells that bring about a response to a stimulus (Ex. Muscle cells) |
|
|
What happens when a) there is too much water in the tissue fluid b) there is too little water in the tissue fluid |
a) Water moves into cells by osmosis, which can cause them to swell and burst b) Water moves out of cells by osmosis, into the tissue fluid, which can slow or stop metabolic reactions inside cells |
|
|
What happens when a) There is a lack of glucose b) There is too much glucose in the tissue fluid |
a) Since glucose provides the energy for respiration inside cells metabolic reactions will slow or stop b) Water will move out of cells by osmosis and into the tissue fluid, slowing or stopping metabolic reactions |
|
|
What happens when a) Temperature is too low b) Temperature is too high |
a) Molecules have less energy to collide with, so collisions are less frequent and less likely to occur with sufficient energy to produce a reaction, so metabolic reactions are slowed (could specifically link to enzymes and substrates) b) Enzymes are denatured - the Hydrogen bonds break resulting in the loss of the specific 3D shape. The shape of the active site is altered. Metabolic reactions are slowed/stopped. |
|
|
Outline Negative Feedback |
* Parameter too high * Receptor detects this * Effector detects this * Response to decrease parameter * Parameter too low * Receptor detects this * Effector detects this * Response to increase parameter * Parameter too high... etc |
|
|
What is positive feedback? Give some examples. |
Positive Feedback is a response which augments the change that occurs. Example 1- If a person breathes air with a high concentration of CO2, receptors detect this and an effector causes increased breathing rate - resulting in greater inhalation of air with a high concentration of CO2 = increased breathing etc Example 2- Cervix dilation Example 3- Blood clotting |
|
|
What is a)Conduction b)Convection c)Radiation? |
a) When particles bump into each other, they transfer heat: the better a conductor the substance is, the greater the rate of conduction b) When a liquid/gas becomes hotter, it becomes less dense and so will rise through the surrounding cooler air c) All objects emit IR. The hotter a substance is the more IR it emits. IR is absorbed as it heats solid objects as it passes through. |
|
|
What are the two types of receptors for temperature change in endotherms? |
* The hypothalamus - detects changes in core temperature by monitoring the temperature of the blood running through it * Peripheral receptors/Skin Receptors- detect changes in the temperature of the environment to give warnings to large changes in core temperature
|
|
|
Draw the heat inputs and outputs of an endotherm. |
|
|
|
Outline the responses that occur when core temperature falls |
* Vasoconstriction - Smooth muscle in the cell walls of arterioles contract, shutting off the blood supply close to the skin to prevent heat loss by radiation/conduction * Shivering - Muscles contract and relax rapidly - this requires energy from ATP which is produced by the oxidation of glucose which results in the loss of some energy as heat * Sweat Glands reduce output of sweat * Behaviour - More clothes, huddling (Reduces surface area, and thus heat loss by radiation) * Erector Muscles - contract so hair stand on ends, trapping a layer of air that is a poor conductor - acts as insulation |
|
|
Outline the responses that occur when core temperature rises |
* Vasodilation - Smooth muscle in the cell walls of arterioles relax, so there is more blood near the skin, so more head is lost by radiation or conduction * Sweat Glands- Increase output of sweat as water has a high latent heat of evaporation and absorbs heat as it evaporates * Behaviour - less clothes, shade, cold beverages, tendency to do less exercise. |
|
|
What is an Ectotherm? Outline one advantage and one disadvantage of being an Ectotherm. |
An Ectotherm is an organism that does not produce heat inside it's body - they obtain most of their heat from their external environment. Advantage - Ectotherms need less food because it is not being used to provide energy to produce heat Disadvantage - Ectotherms are often inactive in cold environments because their cells are also 'cold' and so metabolic reactions are slow. |
|
|
Purple book How do cells communicate with each other? |
Cell signalling - cells release a chemical that is detected by another cell |
|
|
Purple Book Why must an organism coordinate the activities of different organs? |
Groups of specialised cells form tissues and organs that may be in different parts of the body, far from other organs. |
|
|
Purple Book What are the properties of a good communication system? |
- covers whole body
- enables cells to communicate - enables SPECIFIC communication - enables RAPID communication - enables short and long term responses |
|
|
Purple Book What are the two major systems of communication? |
Neuronal system - An interconnected system of neurones that signal across synapse junctions. (rapid) Hormonal system - uses the blood to transport signals. (long-term) |
|
|
Purple Book WHAT DO YOU NOT SAY |
'ALLOWS CONSTANT TEMPERATURE' NO. |
|
|
Purple Book What is an extra purple book advantage of being an ectotherm? |
A greater proportion of the energy obtained from food can be used for GROWTH, |
|
|
Purple Book What do ectotherms do in response to changes in temperature? |
They change their behaviour and physiology to increase/decrease absorption of heat. |
|
|
Purple Book What can ectotherms do to warm up? |
-Bask in sun -Lie on warm surface |
|
|
Purple Book What can ectotherms do to stay cool? |
Stay underground Stay in shade |
|
|
Purple Book How do the following help regulate temp? a) Exposing body to sun b) Orientate body to sun c) Orientate body away from sun d) Hide in burrow e) Alter body shape f) Increase breathing movementd |
a) More heat absorbed b) exposes larger SA = more heat absorption c) lower SA = less heat absorption d) Out of sun = reduces heat absorption e) Exposes less to sun f) Evaporates more water |
|
|
Purple Book What does panting do? |
Increases the evaporation of water from the lungs, tongue and other moist surfaces, using latent heat of evaporation |
|
|
Purple Book What do the liver cells do to maintain body temperature when a) too high b) too low |
a) Rate of metabolism is reduced so less heat is generated from exergonic reactions such as respiration b) Rate of metabolism is increased so respiration generates more heat, which is transferred to the blood |
|
|
Purple Book What is the optimum core temp? |
37 |
