Scaling Up | OCR GCSE Combined Science Biology, Foundation tier (J250)

Scaling Up

147 questions
9 subtopics
Paper 1 (Biology)
Paper 1 (Biology)

Scaling Up is examined in Paper 1 (Biology).

It covers diffusion, osmosis and active transport, mitosis, the cell cycle and cell differentiation, stem cells in animals and meristems in plants, surface area to volume ratio and exchange surfaces, the circulatory system, the heart and blood vessels, red blood cells and plasma, root hair cells, transpiration and translocation, xylem and phloem and factors affecting water uptake, and the potometer.

Sample questions from Scaling Up

Answer each one closed book first, then open the answer.

Diffusion, osmosis and active transport

What happens to a plant cell placed in a concentrated salt solution?

Show the answer
Water leaves it by osmosis, so the cell loses its turgor and the membrane pulls away from the cell wall.
Mitosis, the cell cycle and cell differentiation

Why is mitosis important to an organism that reproduces asexually?

Show the answer
It produces offspring that are genetically identical to the parent.
Stem cells in animals and meristems in plants

What are the two things a stem cell can do when it divides?

Show the answer
It can make more stem cells, or produce cells that go on to differentiate into specialised types.
Surface area to volume ratio and exchange surfaces

Why can a single-celled organism rely on diffusion across its surface alone?

Show the answer
Its surface area to volume ratio is very large and no part of it is far from the surface, so diffusion supplies its needs fast enough.
The circulatory system, the heart and blood vessels

Which vessels carry blood away from the heart and which return it?

Show the answer
Arteries carry blood away from the heart and veins return blood to it.
Red blood cells and plasma

Why does a mature red blood cell have no nucleus?

Show the answer
Leaving it out makes room for more haemoglobin, so each cell can carry more oxygen.
Root hair cells, transpiration and translocation

Explain why mineral ions cannot simply diffuse into a root hair cell.

Show the answer
They are usually more concentrated inside the cell than in the soil water, so they have to be moved against the concentration gradient.
Xylem and phloem

What is lignin and why is it useful in xylem?

Show the answer
It is a tough substance in the vessel walls that strengthens and waterproofs them, holding the tube open and supporting the plant.

The 9 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Diffusion, osmosis and active transport	What diffusion is and why it needs no energy, osmosis and water potential, a plant cell in salt solution, and active transport against a gradient in root hairs and the gut.	20
Mitosis, the cell cycle and cell differentiation	The stages of the cell cycle, DNA replication and why cells grow first, what happens to chromosomes in mitosis and the two identical cells it makes, its roles in growth, repair and asexual reproduction, what cell differentiation is and why it makes organisms efficient, how sperm, nerve, muscle and palisade cells are specialised, how plant and animal cells differ in keeping that ability, and reading percentiles on growth charts.	20
Stem cells in animals and meristems in plants	What stem cells are and where embryonic and adult stem cells are found, what meristems are and where they occur, how stem cells and meristems allow development, growth and repair, bone marrow stem cells replacing blood cells, growing a plant from a cutting, how embryonic and adult stem cells differ, why embryonic stem cells are useful yet controversial, and treating a patient with their own stem cells.	21
Surface area to volume ratio and exchange surfaces	Calculating the surface area, volume and surface area to volume ratio of cubes and blocks, how the ratio falls as organisms get larger, why single-celled organisms rely on diffusion while large animals need exchange surfaces and transport systems, what makes an exchange surface efficient, and the oxygen, carbon dioxide, urea, water, food molecules and mineral ions that organisms take in, transport or remove.	16
The circulatory system, the heart and blood vessels	The job of the circulatory system, the double circulation and its two circuits, its link to gas exchange, the order of arteries, arterioles, capillaries and veins, the four chambers of the heart and the vessels entering and leaving it, the tricuspid, bicuspid and semilunar valves, the thicker left ventricle wall, cardiac muscle, and how arteries, veins and capillaries are adapted to their functions.	18
Red blood cells and plasma	The function of red blood cells, haemoglobin and oxyhaemoglobin, why red blood cells have no nucleus and a flattened disc shape and are small and flexible, what plasma is, the glucose, amino acids, urea and carbon dioxide dissolved in it, how plasma suits its transport role, and the cells, platelets and heat it also carries.	10
Root hair cells, transpiration and translocation	Where root hair cells are and how their shape helps, water entering by osmosis and mineral ions by active transport, transpiration through the stomata and guard cells, and translocation of sugars.	16
Xylem and phloem	What xylem and phloem transport and in which direction, the structure of a xylem vessel, lignin and why dead empty xylem cells help, sieve plates, living sieve tube cells and their companion cells, why transport in phloem needs energy, and how movement in phloem differs from movement in xylem.	10
Factors affecting water uptake, and the potometer	How light, temperature, air movement and humidity change the rate of water uptake, why plants wilt on a hot windy day, and using a potometer to measure and calculate the rate.	16

Scaling Up is 147 of the 806 questions in the guide.Get the guide, £7

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.