Question 1
In a breeding experiment a red – flowered plant was crossed with a white – flowered plant. All the offspring had pink flowers. These pink – flowered plants were selfed. The resultant offspring haf red, Pink and white flowers in the ratios of 1: 2: 1 respectively.
Use letter R to represent gene for red flower colour and W to represent the gene for white colour and answer the following questions.
State the
- State the genotype of :-
- Parents
- F 1 generation
- Work out the cross between plants in the F1 generation
- Explain the occurrence of the colour in the F2 generation
Answer
- State the genotype of :-
- RR & WW;
- RW
-
- 1 Red, 2 Pink, 1 White
there are three colours 1 red 2 pink and 1 white, pink appearing due to incomplete dominance/ co- dominance / equal dominance;
Question 2.
In a physiological experiment, starch, protein, diastase and sodium chloride were added to water and put inside a visking tubing. The visking tubing was then placed in a water bath maintained at a temperature between 35 - 400C. The set up was as shown in the diagram below.
The following observations were made after the procedures indicated.
- Name the process by which salt moved into the water in the beaker from the visking tubing.
-
- Name the food substance responsible for the brown colour observed after 1 hour both in the beaker and visking tubing when solutions are boiled with benedicts solution.
- Account for the observation in (b i) above
-
- Name the food substance tested with sodium hydroxide followed by copper sulphate solution(s)
- Account for the absence of the food substance named in (ci) above in the beaker after 1 hour.
- After one hour the visking tubing was firm. State the term used to describe this state.
Answer
- Diffusion
-
- Reducing sugars.
- Diastase converts starch to reducing sugar; so present in the visking tubing then due to small sized molecules of reducing sugar and semi permeability if visking tubing; the molecules moved across the semi permeable membrane to the beaker; so present both in the visking tubing and the beaker
-
- Proteins
- The molecules of proteins are large / big so cannot pass through the pores of the semi – permeable membrane Visking tubing
- Turgid
Question 3
- Distinguish between natural and acquired immunity
- Define the term allergy
- The chart below shows the blood clotting mechanism
- Name the blood cells represented by x
- The end product of the mechanism represented by Z.
- Explain how the following environmental factors increase the rate of transpiration
- Temperature
- Humidity
- Atmospheric Pressure
Answer
- Allergy – Drastic reaction of the body seen in a few individuals towards foreign substances that are normally harmless to the rest of the population / hypersensitive reaction of the body to harmless substances
-
- Platelets
- Fibrin clot
- Explain how the following environmental factors increase the rate of transpiration
- High temperature in the atmosphere causes temperature of the leaf to rise, thus increasing the vapour pressure in the intercellular air spaces, this causes increase in transpiration rate
- Low humidity in the at atmosphere / dry air, results to higher vapour in the intercellular space than the air surrounding the leaf, hence increases diffusion gradient hence higher transpiration rate
- Low atmospheric pressure; causes an increase in evaporation from a wet surface /less opposing pressure to evaporating molecules thus higher rate of transpiration
Question 4
The diagram below shows a section through the mammalian skin
- Name the parts labeled E and F
-
State the functions of the secretions produced by
- structure H
- structure I
-
Explain how the structures listed below help in regulation of body temperature on a hot day
- structure H
- Structure G
- Apart from excretion and temperature regulation in man, state two other functions of the mammalian skin.
Answer
- E – malpighian layer
F- Nerve endings -
- Structure H – Sweat from it evaporates leading to cooling the body
- Structure I: Makes the hair water repellant / Waterproof
-
- H - Sweat glands – become more active thus secrete more sweat that evaporates, bringing about cooling of the body
- G – Erecter pill muscle, relaxes thus lowering the hair, no / little air is trapped and thus heat is lost
- - Acts as a storage organ for fats
- Mechanical barrier / Protection against entry of pathogens
Question 5
Describe causes and methods of controlling water pollution.
Answer
Domestic effluents; sewage / faeces / urine
- Nitrogeneous wastes / Urea / Uric acid/ Ammonia;
- Garbage; detergent; pollute water.
- Pollution from domestic affluent- controlled by treating domestic wastes
- Using biotechnology;
- Banning use of phosphate – based detergent;
- use of plastic pipes – instead of lead pipes.
- Recycling garbage;
- Industrial waste; radioactive wastes;
- Industrial wastes have heavy metals which include lead/ zinc / copper/
- Chromium mercury; Treating industrial wastes; Carrying out environmental assessment before establishing industries;
- Hot water; cooling hot water;
- Oil spills; controlled by cleaning oil spills/ Biotechnology; Penalising
- industrial / Industries / companies causing pollutions;
- Agrochemicals; such inorganic fertilizers; herbicides/Insecticides/ Pesticides / Fungicides;
- Pollution due to agrochemicals – controlled by mechanical control of weeds; biological control of weeds / pests; use of biodegradable organic fertilizer / herbicides/ insecticides/ organic farming/ Educating farmers on correct amout of agrochemicals;
- Sitting; soil erosion; controlled by appropriate farming practices / contour farming/ reforestation/ building gabions/ terracing;
- Nitrogeneous wastes / Urea / Uric acid/ Ammonia;
- Garbage; detergent; pollute water.
- Pollution from domestic affluent- controlled by treating domestic wastes
- Using biotechnology;
- Banning use of phosphate – based detergent;
- use of plastic pipes – instead of lead pipes.
- Recycling garbage;
- Industrial waste; radioactive wastes;
- Industrial wastes have heavy metals which include lead/ zinc / copper/
- Chromium mercury; Treating industrial wastes; Carrying out environmental assessment before establishing industries;
- Hot water; cooling hot water;
- Oil spills; controlled by cleaning oil spills/ Biotechnology; Penalising
- industrial / Industries / companies causing pollutions;
- Agrochemicals; such inorganic fertilizers; herbicides/Insecticides/ Pesticides / Fungicides;
- Pollution due to agrochemicals – controlled by mechanical control of weeds; biological control of weeds / pests; use of biodegradable organic fertilizer / herbicides/ insecticides/ organic farming/ Educating farmers on correct amout of agrochemicals;
- Sitting; soil erosion; controlled by appropriate farming practices / contour farming/ reforestation/ building gabions/ terracing;