Yr 10 Science Exam Revision Answers
BIOLOGY SECTION
1. A red flower is crossed with a white flower. Red is dominant to white.
Q- What is the genotypic ratio of the first generation?
A- 100% Rr.
Q- What is the phenotypic ratio of the second generation?
A- 75% Red; 25% White OR 3Red : 1 White.
2. A moth has produced an egg with 32 chromosomes.
Q- How many chromosomes does the male sperm have?
A- 32.
Q- A female can produce offsprings without a male. What is the name of this form of asexual reproduction?
A- Parthenogenesis.
Q- How many chromosomes does a fertilised egg contain?
A- 64.
3. A red guinea pig is mated with a white guinea pig. All the first generation offprings were pink.
Q- What type of inheritance is displayed in the above example?
A- Intermediate inheritance.
Q- What could be said about the two colours involved?
A- They are co-dominant.
Q- If two pigs from the first generation are mated. Determine the genotypic ration.
A- 25%RR; 50%RW; 25%WW.
4. A tall pea plant is crossed with a short pea plant. From the first generation, 50% were pure and 50% were hybrid.
Q- Determine the genotypes of the parents.
A- Tt and tt.
Q- Write the genotype of a homozygous tall plant.
A- TT.
5. Identify the name of asexual reproduction used by the following organisms.
Q- Hydra and Yeast
A- Budding.
Q- Bacteria.
A- Binary fission.
Q- Fungus and ferns and algae.
A- Spores.
Q- Potato.
A- Tubers.
6. A flower contains two structures: a pistil and a stamen.
Q- Name the structures within the stamen.
A- filament and anther.
Q- Where is pollen stored?
A- anther.
Q- Name the structures that make up the pistil.
A- stigma, style and ovary.
Q- Define the term pollination.
A- The transfer of pollen from an anther to a stigma.
Q- Two male nuclei join with the two female nuclei in the ovary to produce …
A- a seed and a fruit.
Q- Name the location where a female nucleus develops into seed.
A- The ovule.
Q- Name the function of a flower.
A- Reproduction.
Q- Name the process whereby pollen is transferred from one flower to another on the same cherry tree.
A- Self-pollination.
7. A chromosome is a structure that holds our genetic information.
Q- Name the chemical that makes up a chromosome.
A- DNA.
Q- Name the chemical that pairs off with cytosine.
A- Guanine.
Q- Name the two substances that make up the backbone of a chromosome.
A- Sugar and phosphate.
Q- How many chromosomes are found in a human bone cell?
A- 46.
Q- Name the place where sperm is stored.
A- Testes.
Q- Sperm and ova are known as:
A- Gametes.
Q- Define a zygote.
A- A fertilised egg.
Q- How many sets of chromosomes does a haploid cell have?
A- One set.
Q- Name the type of cell division that gives rise to variation.
A- Meiosis.
Q- Complete the following table. (Change font colour to black for the answers).
Meiosis / MitosisType of daughter cell / Haploid / Diploid
Number of cell divisions / 2 / 1
Place of occurrence / Gonads / Everywhere
State of daughter cells / Various / Identical
Number of daughter cells / 4 / 2
8. Clive and Isabelle are married with two sons Jordan and Tony and a daughter Lisa. Clive has attached ear lobes. His father has free ear lobes. Free ear lobes(E) is dominant to attached ear lobes(e).
Q- What is the genotype of clive’s father?
A- Ee.
Q- What is the genotype of Clive?
A- ee.
Q- Jordan has free ear lobes. What is his genotype?
A- Ee.
Q- Tony has attached ear lobes. What is his mother’s genotype?
A- Ee.
Q- What gene did Jordan get from his mother?
A- E.
Q- Lisa has attached ear lobes. What gene did she get from her father?
A- e.
Lisa marries Fred who has no history of attached ear lobes in his family.
Q- What is the probability of them having children who are homozygous attached ear lobes?
A- 0%.
Q- Free ear lobes?
A- 100%.
CHEMISTRY SECTION
1. Elements are presented in vertical columns (groups) and horizontal rows (periods).
Q- Name a chemical found in the third group and the third period.
A- Aluminium.
2. Isotopes are elements with different number of neutrons.
Q- How many neutrons does carbon 12 have?
A- 6.
Q- How many neutrons does carbon 14 have?
A- 8.
3. Ions are atoms that have gained or lost electrons.
Q- Which of the following chemical formulae are ionic compounds?
Na2CO3 KCl NH3 NH4OH CH3COOH N2P5 CO2
A- Na2CO3 KCl NH4OH(crystal form)
Q- Complete the following table. (Change font colour to black for the answers).
Ions/atoms / Atomic number / Mass number / Number of electrons / Number of neutronsCa / 20 / 40 / 20 / 20
K+ / 19 / 18 / 20
S2- / 16 / 32 / 18 / 16
Cu / 29 / 63 / 29 / 34
4. Dot diagrams show the number of valence electrons involved in bonding.
Q- Draw the dot diagram showing ionic bonds in the compound CaCl2.
Cl Ca Cl
_ +2 _
A- Cl Ca Cl
Remove this block to reveal the answer.
Q- Use the dot diagram to show covalent bonding in the molecule BF3.
O C O
A- O C O
Remove this square to reveal the answer
5. Metals usually take the positive valence sign when they become ions.
Q- Underline those that are classified as metal ions.
Na+ Mg2+ F- S2- NH4+ H+ Al3+ OH- CO32-
A- Na+ Mg2+ Al3+
6. Metals react with acid to produce hydrogen gas and salt.
Q- Complete the following chemical reaction.
Al + H2SO4 ______+ H2
A- 2Al + 3H2SO4 Al2(SO4)3 + 3H2
Q- Complete the following chemical reaction.
Zn + ______Zn3(PO4)2 + H2
A- Zn + H3PO4 Zn3(PO4)2 + H2
Q- Balance the following chemical reaction.
Al + H2SO4 Al2(SO4)3 + H2
A- 2Al + 3H2SO4 Al2(SO4)3 + 3H2
Q- Balance the following chemical reaction.
Cu(II) + H3PO4 CuPO4 + H2
A- 3Cu + 2H3PO4 Cu3(PO4)2 + 3H2
7. Metal oxides and hydroxides react with acid to produce salt and water.
Q- Complete the following chemical reactions.
CuO + HNO3 ______+ H2O
A- CuO + 2HNO3 Cu(NO3)2 + H2O
Q- Complete the following chemical reactions.
PbO + HCl ______+ ______
A- PbO + 2HCl PbCl2 + H2O
Q- Balance the following chemical reaction.
CuO + HNO3 Cu(NO3)2 + H2O
A- CuO + 2HNO3 Cu(NO3)2 + H2O
Q- Balance the following chemical reaction.
Al(OH)3 + H2SO4 Al2(SO4)3 + H2O
A- 2Al(OH)3 + 3H2SO4 Al2(SO4)3 + 6H2O
8. When solutions are mixed together, sometimes a precipitate form. The ions responsible for the formation of the precipitate are written in an ionic equation.
Q- Write an ionic equation for these two solutions, if no precipitate forms, write NR.
Pb(NO3)2 + K2SO4
A- Pb2+ + SO42- PbSO4
(aq) (aq) (S)
Q- Write an ionic equation for these two solutions, if no precipitate forms, write NR.
CaBr2 + K2S
A- Ca2+ + S2- CaS
(aq) (aq) (S)
Q- Write an ionic equation for these two solutions, if no precipitate forms, write NR.
Na2CO3 + CuSO4
A- Cu2+ + CO32- CuCO3
(aq) (aq) (S)
9. Write the name and formula of the salt formed.
Reactants / Name of salt / Formula of saltSodium & nitric acid / Sodium nitrate / NaNO3
Lead oxide & hydrochloric acid / Lead chloride / PbCl2
Calcium carbonate & acetic acid / Calcium acetate / Ca(CH3COO)2
PHYSICS SECTION
Q1- A bike travelling at 11m/s brakes uniformly at 1.65m/s2 for 5 seconds in coming to a rest at a stop sign. At what distance from the sign did the bike commence braking?
A- a = 1.65m/s2 ; t = 5 seconds; u = 11m/s; v = 0m/s
S = ut + ½ at2
= 11(5) + ½ 1.65(5) 2
= 55 + 20.625
= 75.625 m.
A ball has been dropped. It bounces with a velocity of 3.5m/s, decelerating at 2.4m/s2. It takes 1.8 second before it reaches its highest potential energy.
Q2- Calculate the total distance from the moment of retardation until the moment it attains the highest potential energy.
A- a = 2.4m/s2 ; t = 1.8 seconds; u = 3.5m/s;
s = ut + ½ at2
= 3.5(1.8) + ½ (-2.4)(1.8) 2
= 6.3 - 3.89
= 2.41m
Q3- Determine the average speed for the ball.
A- Vav = s/t
= 2.41/1.8
= 1.33m/s
Q4. What distance does a skier travel in the sixth second of motion if when moving at 4m/s she accelerates at 1.6m/s2?
A- a = 1.6m/s2 ; t = 5 seconds; u = 4m/s; [distance at five seconds]
S = ut + ½ at2
= 4(5) + ½ 1.6(5) 2
= 20 + 20
= 40m.
a = 1.6m/s2 ; t = 6 seconds; u = 4m/s; [distance at six seconds]
S = ut + ½ at2
= 4(6) + ½ 1.6(6) 2
= 24 + 28.8
= 52.8m.
Distance travelled in the sixth second = 52.8 – 40 = 12.8m.
A truck travelling at 42m/s is decelerated uniformly at1.8m/s2.
Q5- Calculate the velocity after 5 seconds.
A- u = 42m/s; a = 1.8m/s2; t = 5 seconds.
a = v - u
t
-1.8 = v - 42
5
v = -1.8(5) + 42
= -9 + 42
= 33m/s
Q6- Calculate the time taken to come to rest.
A- a = v - u
t
t = v - u
a
= 0 - 42
-1.8
= 23.3 seconds.
Q7. Determine the time it takes to accelerate a train from 29km/h to 120km/h at 3.5m/s2.
A- u = 29/3.6 = 8.06m/s;
v = 120/3.6 = 33.33m/s
a = v – u \ t = v - u
t a
= 33.33 – 8.06
3.5
= 7.22 seconds.
The graph below represents the motion of two horses travelling from the same position.
Horse 1 =
Horse 2 =
2 4 6 8 10 12
Q8. What is the velocity of horse 1 in the first 2 seconds?
A- v = s/t
= 3/2
= 1.5m/s.
Q9. What is the velocity of horse 1 in the next three seconds?
A- v = s/t
= 1/3
= 0.33m/s.
Q10. What is the velocity of horse 2 in the first 3 seconds?
A- v = s/t
= 6/3
= 2m/s.
Q11. How far did horse 2 travel in the first 8 seconds?
A- 6 +2 +2 = 10m.
Q12. What is the average velocity of horse 2 in the first 13 seconds?
A- v = s/t
= 0/13
= 0 m/s.
Q13. What is the average velocity of horse 1 in the first 10 seconds?
A- v = s/t
= 7/10
=0.7m/s
Q14. Determine which horse had the highest average speed for the 13 seconds.
A- v = s/t horse 1
= 10/13
=0.77m/s
v = s/t horse 2
= 16/13
=1.23m/s
Horse 2 had the highest average speed.
Q15- For how long did horse 1 stay stationary?
A- 5 seconds.
Q16- Calculate the velocity of horse 2 in the last 5 seconds.
A- v = s/t = 6/5 =1.2m/s
Q17. Calculate the acceleration from the ticker timer tape.
The frequency is 1/50 Hz.
A- S1 = 1.1cm = 0.011m
S2 = 2.65cm = 0.0265m
u = s/t
= 0.011/.08 (4x 0.02)
= 0.1375m/s
v = s/t
= 0.0265/0.08 (4x 0.02)
= 0.33125m/s
a = v - u
t
= 0.33125 – 0.1375
0.88 (0.02 x 44)
= 0.19375m/s2 .
Disregard the negative sign. It’s because you’re dividing by a number smaller than 1.
Q18- Define the term ‘motion’.
A- Motion is the movement of one object in relation to another object which is at rest.
Q19- List four scalar quantities.
A- Volume, area, speed and mass.
Q20- Determine the displacement of the truck, using trigonometry.
A truck moving 130km West then 280km South.
A- Firstly, determine the displacement.
q a2 + b2 = c2
1302 + 2802 = c2
c 16900 + 78400 = c2
95300 = c2
c = Ö95300 = 308.7km
secondly, calculate the angle of displacement
tan q = 280 / 130
= 2.15
q = tan-1 2.15
= 65°.
The truck moved 308.7km West 65° South.
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