Attnom Academy assessment paper, Level 4

Science, about class 9

  • Time: 60 minutes
  • 40 marks
  • 25 questions

This paper tests only the chapters below. Read them first. Each question names its chapter in the mark scheme, so a lost mark tells you what to read again.

Sit it here and mark it on this device, or print it on A4 with its mark scheme. The class is a guide: the books are written in levels.

Section A. Quick recall (12 marks)

Tick one answer for each question. Each question is worth 1 mark.

Question 11 mark

Mei says that plant cells have no mitochondria, because plants make their own food. Which reply is right?

Question 21 mark

Leila leaves a limp lettuce leaf in a bowl of plain water. An hour later it is crisp. Why did the leaf cells gain water?

Question 31 mark

A gut cell makes a protein called lactase. Where in the cell is the code for lactase kept?

Question 41 mark

A sperm cell that carries a Y chromosome joins an egg cell. What sex chromosomes does the new cell have?

Question 51 mark

A scientist compares the same 40 bases of DNA in four species. Species P differs from Q at 3 bases, from R at 9 bases and from S at 14 bases. Which species is the closest relative of P?

Question 61 mark

A kind of snake reaches an island in the cargo of a plane. The island had no snakes before. Over the years the snakes eat most of the forest birds that live only on that island, and several kinds die out. Which cause of extinction is this?

Question 71 mark

The horse is Equus caballus, the donkey is Equus asinus and the cow is Bos taurus. Which statement is right?

Question 81 mark

A lab report describes a pathogen. It is genetic material inside a protein coat, and it has no cytoplasm or cell wall. What kind of pathogen is it?

Question 91 mark

Tariq breathes in dusty air and pathogens in a busy market. How do his airways deal with them?

Question 101 mark

A dog barks suddenly behind Ana. Her heart beats faster and she breathes faster. Which gland releases the hormone that prepares her body, and which hormone is it?

Question 111 mark

An atom of phosphorus has atomic number 15 and mass number 31. How many neutrons does it have?

Question 121 mark

A neutral atom has 14 electrons. Number the groups as your science book does. In which group and period of the periodic table is it?

Section B. Worked problems (20 marks)

Show your working. Write the answer with its unit. The marks for each question are shown beside it.

Question 132 marks

Ana studies a mitochondrion in an electron micrograph. In the picture it is 12 mm long. The magnification is ×6 000. How long is the real mitochondrion, in micrometres?

Question 141 mark

Suppose one cell divides by mitosis every 2 hours, and none of the cells die. How many cells has this one cell become after 14 hours?

Question 151 mark

In a sample of DNA, 18% of the bases are G. What percentage of the bases are T?

Question 161 mark

A body cell of maize has 10 pairs of chromosomes. How many different sex cells can random sorting alone make?

Question 172 marks

A farmer sprays a field with an insecticide. It kills almost all the insects. The next year the same spray kills far fewer of them. Use natural selection to explain why.

Question 182 marks

A town of 5 000 people had 200 cases of cholera in a year. After it built a clean water supply, it had 50 cases in a year. By how many cases for every 1 000 people did the yearly cases fall?

Question 192 marks

Suppose about 85 in every 100 people must be immune to stop a disease spreading. A town has 1 200 people. Of them, 900 are immune now. How many more people must become immune?

Question 202 marks

A cricketer sees a ball coming and swings the bat. Put the parts that the message passes through in order. Start with the part that detects the ball.

Question 212 marks

Ana catches a falling ruler at 8 cm. Her brother catches it at 23 cm. Use t = √(2d ÷ g), with d in metres and g = 9.8 m/s². Round each time to the nearest millisecond. How many milliseconds longer is his reaction time?

Question 222 marks

Ravi's pupil is 5 mm wide in dim light. What is its area in mm², to 1 decimal place? Use A = π × r × r, where r is half the width.

Question 231 mark

In one run of the gold foil experiment, 28 000 alpha particles hit the foil. About 4 of them bounce back. About how many alpha particles hit the foil for each one that bounces back?

Question 242 marks

Copper is 69% copper 63 and 31% copper 65. Find its relative atomic mass to one decimal place.

Section C. A longer question (8 marks)

Each part uses the same story. Show your working.

Question 258 marks

Ana adds 2.6 g of zinc to an excess of hydrochloric acid in a school laboratory, with her teacher. Hydrogen gas bubbles off and zinc chloride forms. The acid burns skin and eyes, so she wears goggles and gloves. The hydrogen catches fire easily, so there are no flames nearby. Do not try this at home. The relative atomic masses are Zn 65, H 1 and Cl 35.5.

(a)Zinc ions are Zn²⁺ and chloride ions are Cl⁻. How many chloride ions are in 5 units of zinc chloride? [1 mark]

(b)The equation Zn + HCl → ZnCl₂ + H₂ is not balanced. Balance it. Then say how many molecules of HCl react with 3 atoms of zinc. [1 mark]

(c)Ana weighs 3.4 g of zinc chloride, ZnCl₂. How many moles of zinc chloride is that? [2 marks]

(d)Ana collects 4.08 g of zinc chloride from the 2.6 g of zinc. Use the balanced equation from part b. What is her percentage yield? [2 marks]

(e)Why is Ana's percentage yield less than 100%? Give two reasons. [2 marks]

0 of 29 answered. Your answers stay on this device.

The whole mark scheme, for a teacher or for after you mark

Mark scheme

One line is one mark. A right final answer with no working gets every mark for that part. Lost marks? Read the chapter named under the part.

Question 11 mark

Answer: C. She is wrong. Plant cells also release energy in their mitochondria.

  1. Plant cells release energy from glucose by respiration, and this happens in their mitochondria, as in animal cells.

Tests S4.1.1 Cell structure in detail

Question 21 mark

Answer: A. Water crossed the membrane by osmosis, from the plain water into the more concentrated cell contents.

  1. Osmosis moves water across a partially permeable membrane from a dilute solution, here the plain water, to a more concentrated one, the cell contents.

Tests S4.1.3 Diffusion, osmosis and active transport

Question 31 mark

Answer: B. In a gene, a section of DNA on a chromosome in the nucleus.

  1. A gene is a section of DNA with the code for one protein. It sits on a chromosome in the nucleus.

Tests S4.2.1 DNA, genes and chromosomes

Question 41 mark

Answer: D. XY

  1. The egg always gives an X and this sperm gives a Y, so the new cell is XY.

Tests S4.2.4 Boy or girl: X and Y

Question 51 mark

Answer: B. Species Q

  1. The fewer the differences in the DNA, the closer the relation. Q differs at the fewest bases.

Tests S4.3.2 Evidence for evolution

Question 61 mark

Answer: C. An invasive species

  1. People carried the snakes to a new place, where they harm the local living things. That is an invasive species.

Tests S4.3.3 New species and extinction

Question 71 mark

Answer: A. Equus caballus and Equus asinus share a genus but are different species.

  1. The first word is the genus, and they share Equus. The second word is the species, and caballus and asinus differ.

Tests S4.3.4 Classification

Question 81 mark

Answer: D. A virus

  1. A virus is genetic material in a protein coat. It is not a cell.

Tests S4.4.1 Kinds of disease

Question 91 mark

Answer: D. Mucus traps them, and cilia sweep the mucus out of the airways.

  1. Mucus traps pathogens and dust. Cilia sweep the mucus out of the airways.

Tests S4.4.3 The body's defences

Question 101 mark

Answer: C. The adrenal glands, which release adrenaline

  1. The adrenal glands release adrenaline, which gets the body ready for danger.

Tests S4.5.4 Hormones

Question 111 mark

Answer: A. 16 neutrons

  1. Neutrons = mass number − atomic number, so 31 − 15 = 16 neutrons.

Tests S4.6.1 Inside the atom

Question 121 mark

Answer: B. Group 4, period 3

  1. The electrons fill shells as 2, 8, 4. The outer shell has 4 electrons, so the group is 4. There are 3 shells, so the period is 3.

Tests S4.6.4 Electron shells

Question 132 marks

Answer: 2 µm

  1. Real size = image size ÷ magnification. The image is 12 mm, which is 12 × 1 000 = 12 000 µm.
  2. 12 000 ÷ 6 000 = 2 µm.

Tests S4.1.2 Microscopes and size

Question 141 mark

Answer: 128 cells

  1. There are 14 ÷ 2 = 7 divisions, and each one doubles the cells: 2 × 2 × 2 × 2 × 2 × 2 × 2 = 128 cells.

Tests S4.1.4 Cell division

Question 151 mark

Answer: 32%

  1. G pairs with C, so 18% are C. That leaves 100 − 18 − 18 = 64% for A and T together, and T is half of it: 64 ÷ 2 = 32%.

Tests S4.2.2 The structure of DNA

Question 161 mark

Answer: 1 024 sex cells

  1. Each pair can sort in 2 ways, so the number is 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 = 1 024.

Tests S4.2.3 Meiosis and sex cells

Question 172 marks

Answer: A few insects had an allele that made them resistant to the spray, by chance. They survived and bred, and passed on the allele. So more of the next generation are resistant.

  1. Says a few insects already had an allele for resistance, by chance, so the spray did not kill them.
  2. Says the resistant insects survived and bred and passed on the allele, so more of the next generation are resistant.

Tests S4.3.1 Natural selection

Question 182 marks

Answer: 30 cases

  1. The cases fell by 200 − 50 = 150.
  2. For every 1 000 people: 150 ÷ 5 000 × 1 000 = 30 cases.

Tests S4.4.2 How diseases spread

Question 192 marks

Answer: 120 people

  1. 85 in every 100 of 1 200 people is 85 ÷ 100 × 1 200 = 1 020 people.
  2. 1 020 − 900 = 120 more people.

Tests S4.4.4 Vaccination

Question 202 marks

Answer: The receptor in the eye detects the ball. A sensory neurone carries the impulse to the brain. The brain sends an impulse along a motor neurone to the effector, a muscle in the arm, which swings the bat.

  1. Gives the receptor in the eye, then a sensory neurone, then the brain, in that order.
  2. Then gives a motor neurone, then the effector, a muscle in the arm.

Tests S4.5.1 The nervous system

Question 212 marks

Answer: 89 ms

  1. The ruler fell 0.08 m for Ana and 0.23 m for her brother. Using t = √(2d ÷ g), her time is 0.128 s, which is 128 ms, and his is 0.217 s, which is 217 ms.
  2. 217 − 128 = 89 ms.

Tests S4.5.2 Reflexes

Question 222 marks

Answer: 19.6 mm²

  1. The radius is half the width: 5 ÷ 2 = 2.5 mm.
  2. A = π × 2.5 × 2.5 = 19.6 mm².

Tests S4.5.3 The eye

Question 231 mark

Answer: 7 000 alpha particles

  1. 28 000 ÷ 4 = 7 000 alpha particles for each one that bounces back.

Tests S4.6.2 How the model of the atom changed

Question 242 marks

Answer: 63.6

  1. Multiply each mass number by its percentage and add: 69 × 63 = 4 347 and 31 × 65 = 2 015, and 4 347 + 2 015 = 6 362.
  2. Divide by the total of the percentages: 6 362 ÷ 100 = 63.62, which is 63.6 to one decimal place.

Tests S4.6.3 Isotopes

Question 258 marks

(a)Answer: 10 ions

  1. One Zn²⁺ ion needs two Cl⁻ ions to cancel its charge, so 5 units hold 5 × 2 = 10 chloride ions.

Tests S4.7.1 Chemical formulae

(b)Answer: 6 molecules

  1. The balanced equation is Zn + 2HCl → ZnCl₂ + H₂, so each zinc atom needs 2 HCl molecules, and 3 × 2 = 6 molecules.

Tests S4.7.2 Balancing equations

(c)Answer: 0.025 mol

  1. Relative formula mass of ZnCl₂ = 65 + 35.5 + 35.5 = 136.
  2. Moles = mass ÷ Mr = 3.4 ÷ 136 = 0.025 mol.

Tests S4.7.3 The mole

(d)Answer: 75%

  1. Moles of zinc = 2.6 ÷ 65 = 0.04 mol. The equation shows 1 mol of zinc makes 1 mol of zinc chloride, so the theoretical yield is 0.04 × 136 = 5.44 g.
  2. Percentage yield = 4.08 ÷ 5.44 × 100 = 75%.

Tests S4.7.4 Reacting masses and yield

(e)Answer: Some zinc chloride stays on the glass or the filter paper when it is moved. Some may also stay dissolved in the liquid, so it never reaches the scale.

  1. Gives one reason, such as some product is lost on the glass or the filter paper when it is moved.
  2. Gives a second reason, such as some product stays dissolved, the reaction stops before the reactants are used up, or another reaction makes a different product. Atoms or mass being destroyed earns no mark.

Tests S4.7.4 Reacting masses and yield