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PART II
[60 marks]
Answer four (4) questions from this section.
2. (a) (i) Which organ controls blood circulation in mammals?
(ii) State two (2) functions
of this organ.
(iii) Name two (2) diseases of the organ named in (a)(i) above.
(b) (i) Name two (2) devices which can convert electrical energy into heat
(ii) What is the working resistance of a bulb that takes a current of 0.25
when it is connected to the 220V mains supply?
(c) (i) What is the role of acids in biological systems such as digestion?
(ii) Kofi wants to measure the acidity of a substance, what instrument w
needs and how does the instrument relate to acid strength?
(d) How do human activities like deforestation and intensive farming impa
soil health?
3. (a) (i) How do nitrogen-fixing bacteria contribute to soil fertility?
(ii) List two (2) examples of nitrogen fixing bacteria.
(b) (i) What are the basic components of an electrical circuit?
(ii) How do series and parallel circuit differ in terms of resistance and
current flow?
(c) (i) Compounds are chemically combined of two or more elements.
Ham State two (2) characteristics of compound.
(ii) Name two (2) examples of compound used in
(a) home
(B) pharmaceutical
(d) (i) Mosquito undergoes four stages in its life cycle. State how long doe
each stage typically last.
(ii) Environmental factors affect the mosquito life cycle, name two (2)
such environmental
factors.
4. (a) (i) What is the relationship between force, mass and acceleration accor
to Newton's second law?
(ii) A car accelerates from 0 to 60km/h in 10 seconds with mass 200kg.
What is the
average force applied?
(b) (i) What are the stages of water cycle?
(ii) A farmer wants to conserve water for irrigation. State two (2) ways
use efficient irrigation
system.

Sagot :

GinnyAnswer

Final answer:

The heart controls blood circulation, converts electrical energy into heat devices, roles of acids in biological systems, and impacts of human activities on soil health.


Explanation:

(a) (i) The organ that controls blood circulation in mammals is the heart.

(ii) Two functions of the heart are pumping oxygenated blood to the body and receiving deoxygenated blood from the body.

(iii) Two diseases of the heart are coronary artery disease and heart failure.

(b) (i) Two devices that can convert electrical energy into heat are electric heaters and electric stoves.

(ii) The formula for calculating resistance (R) is R = V/I. For a bulb taking 0.25A current at 220V, the resistance would be 220/0.25 = 880 ohms.

(c) (i) Acids in biological systems, like digestion, help in breaking down food and aiding in nutrient absorption.

(ii) To measure acidity, Kofi needs a pH meter, and the instrument's readings correlate with acid strength.

(d) Human activities like deforestation and intensive farming can lead to soil erosion, loss of biodiversity, and depletion of essential nutrients, impacting soil health negatively.


Learn more about Blood circulation in mammals and related concepts here:

https://brainly.com/question/30972670


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