Yr 10 Science Exam Revision Answers

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).

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).

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.

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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