Chapter 12 Homeostasis -tutorial Worksheet

Jurongville Secondary School Secondary 3 Express Biology Tutorial Syllabus 5100 Name: _________________________ (

)

Class: Sec 3___ Chapter 12: 1.

Date: ____________

Homeostasis

Fill in the blanks with appropriate words. a. Homeostasis is the ________________ of a _____________ internal environment. Internal environment refers to the _____________ that bathe the cells in out body. b. Keeping a constant _____________ pressure is an example of _____________ control. This control involves a ___________ in the internal environment, a ____________ mechanism and a ________________ feedback.

2.

The methods of temperature regulation in our body are listed in (a) to (f). Beside each method indicate if it brings about heat loss, heat conservation or heat production. a. Vasodilation of arterioles in skin

_____________________

b. Profuse sweating

_____________________

c. Vasoconstriction of arterioles in skin _____________________ d. Shivering

_____________________

e. High metabolic rate

_____________________

f.

_____________________

Very little sweating

Structured Questions 3.

The diagram shows the structure of human skin. a. Name A to G. i. A: ___________________ ii. B: ___________________ iii. C: ___________________ iv. D: ___________________ v. E: ___________________ vi. F: ___________________ vii. G: ___________________ b. During vigorous exercise, the skeletal muscles generate a lot of heat.

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i. How does this affect the body temperature immediately? ____________________________________________________________ ii. If the body temperature is not brought back to normal what would happen? ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ iii. Name the 2 structures in the skin that help return the temperature back to normal and explain how they do it. ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ iv. What happens to the 2 structures if you walk into a cold room? Explain the purpose of these effects you have stated. ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ c. i. What is the maintenance of a constant internal environment known as? __________________________________________ ii. What is its control centre? ____________________________________________________________ iii. What organs will this center instruct to take corrective measures if the blood flowing through it has too much water, too little glucose and too much carbon dioxide? ____________________________________________________________

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d. Study the table below.

Arctic fox African bat-eared fox

Temperature of environment (°C) 0 25

Body temperature (° C) 37 37

Ear size Small Large

i. How is the ear size of these animals adapted to suit their environment? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ ii. Your hands and feet feel colder than the rest of your body on a cold day indicating that the skin temperature in these regions is lower than most parts of the body. Why is this so? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 4.

The following table shows 4 ways whereby water leaves through the body and the amounts lost on a day in summer and in winter. Water loss (cm3) Winter Summer Breath 350 The same as Skin 450 Urine 1300 Faeces 140 a. i. Fill in the table to show whether the amount of water lost in summer would be lower, higher or the same as on a winter day. The first one has been filled in. ii. Name the process whereby water is lost from the skin. ____________________________________________________________

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b. The body gains 2330 cm3 of water on a cool day, of which 1450 cm3 comes directly from drinking. Give 2 other ways in which the body may gain water. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________

~END OF TUTORIAL~ 4