Name:______________ Grade+Class:_____________ Score: ____________ Homeostasis Worksheet 1. Read through the following passage on homeostasis and then answer the questions. Homeostasis is the regulation of the internal environment within narrow limits. This gives the organism a degree of independence from the external environment. The regulation is carried out by negative and positive feedback mechanisms which when not required are damped. All living organisms possess some powers of homeostasis but homeostasis is best developed in birds and mammals. (a) (i) What do you understand by the term ‘internal environment’? .......................................................................................................................................... .....................................................................................................................................[2] (ii) Distinguish negative feedback control from positive feedback control. .......................................................................................................................................... .......................................................................................................................................... .....................................................................................................................................[2] (iii) Give one example of negative feedback control and one example of positive feedback control in mammals. Negative feedback control: .......................................................................................................................................... Positive feedback control: .....................................................................................................................................[2] (iv) What do you understand by the term ‘damping’? .....................................................................................................................................[1] (b)State one example of homeostatic control in each of the following organisms. Amoeba: ........................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... Marram grass: ........................................................................................................................................... .......................................................................................................................................... 1 Name:______________ Grade+Class:_____________ Score: ____________ .......................................................................................................................................... Human:.............................................................................................................................. .......................................................................................................................................... .....................................................................................................................................[3] 2. The passage below outlines homeostasis.[5’] Complete the passage by using the most appropriate scientific terms. Homeostasis, in mammals, is the process of keeping the ........................................... environment of the body in optimum conditions so that cells can function efficiently. Blood water potential, core temperature and blood glucose concentration are all factors that need to be kept at optimum values or set-point. When a condition deviates from its set-point, a corrective mechanism is triggered. An increase in blood glucose concentration triggers processes to decrease it and vice versa. This corrective mechanism is called ............................................ The pancreas is involved in the control of blood glucose concentration. Glucose binds to ........................................... on the cell surface membrane of pancreatic cells. These are ........................................... cells, which secrete hormones such as insulin and glucagon. The two hormones have opposite effects on the blood glucose concentration. For example the action of one hormone stimulates the uptake of glucose by cells for respiration and the action of the other hormone stimulates the breakdown of ........................................... to glucose in the liver. 2 Name:______________ Grade+Class:_____________ Score: ____________ Nerve Impulses Worksheet (b) Explain, with the aid of the diagram, how a nerve impulse passes along a non-myelinated neuron ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… 3 Name:______________ Grade+Class:_____________ Score: ____________ (c) State what a threshold potential represents ………………………………………………………………………………………… ………………………………………………………..........………………………… 2.Label the diagram of a typical motor neuron [6’] 1 ………………………………………… 2 ………………………………………… 3 ………………………………………… 4 ………………………………………… 5 ………………………………………… Draw direction of nerve impulse 4 Name:______________ Grade+Class:_____________ 5 Score: ____________ Name:______________ Grade+Class:_____________ 6 Score: ____________ Name:______________ Grade+Class:_____________ Score: ____________ Synapses Worksheet 1. Label the diagram and explain the process of synaptic transmission [7’] 1. ………………………………………………………………………... 2. ………………………………………………………………………... 3. ………………………………………………………………………... 4. ………………………………………………………………………... 5. ………………………………………………………………………... 6. ………………………………………………………………………... 7. ………………………………………………………………………... 2. Describe how synaptic transfer enables complex decision making in the CNS[3’] ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… 3. Describe the secretion of acetylcholine [3’] ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… 7 Name:______________ Grade+Class:_____________ Score: ____________ ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… 8
