AS 1 2019-style cell division question · 6 marks
Describe the events of mitosis and explain its importance in a multicellular organism.
Marked instantly, no account needed
CCEA AS Biology 2019 past paper and mark scheme
Summer 2019 is part of the current CCEA GCE Biology (2016) specification, so every question style in it is still examinable. The papers and mark schemes themselves are published by CCEA; BioCCEA is an independent study tool and is not endorsed by CCEA.
What you sit in AS 2019
AS 1: Molecules and Cells
AS 1 written paper (1 hour 30 minutes)
Biological molecules, enzymes, cell structure, transport across membranes, cell division, nucleic acids and the immune response.
AS 1 topic list and exam focusAS 2: Organisms and Biodiversity
AS 2 written paper (1 hour 30 minutes)
Gaseous exchange, transport in plants and mammals, adaptation, biodiversity, classification, sampling and human impact.
AS 2 topic list and exam focusAS 3: Practical Skills in AS Biology
AS 3 practical booklet plus a written practical-skills paper (1 hour)
Planning, manipulating apparatus, recording, processing and evaluating experimental data at AS level.
AS 3 topic list and exam focus
How to sit the 2019 paper properly
- 1Print the paper and sit it in one block, to time, with no notes. A paper done in pieces tells you nothing about your exam performance.
- 2Mark it with the official CCEA mark scheme in front of you and award a mark only where the scheme's point is actually made.
- 3Log every dropped mark by unit topic, not by question number, so patterns appear across papers.
- 4Rewrite the two worst answers in full, using mark-scheme wording, then re-mark them.
- 5Come back to the same paper three weeks later and redo only the questions you lost marks on.
Sit the AS 2019 style questions
Answer each one under exam conditions. Your wording is marked against every mark scheme point before the full-mark answer appears.
1/3
These questions are written in the style of the CCEA GCE Biology (2016) papers and are not reproduced from any live paper. CCEA owns the copyright in its question papers and mark schemes — always download the official paper and mark scheme from CCEA and use these worked answers alongside them. BioCCEA is an independent study tool and is not endorsed by CCEA.
Worked AS 2019 questions with mark schemes
Question styles that carried the most marks in the Summer 2019 papers, each with the full list of creditworthy mark scheme points, a model answer at full marks, and the marking point candidates most often missed.
AS 1 2019-style cell division question · 6 marks
Describe the events of mitosis and explain its importance in a multicellular organism.
Command word: Describe — how to answer itMark scheme — 6 creditworthy points
- Prophase: chromosomes condense and become visible as two sister chromatids; nuclear envelope breaks down
- Metaphase: chromosomes line up on the equator, attached to spindle fibres by their centromeres
- Anaphase: centromeres divide and sister chromatids are pulled to opposite poles by the spindle fibres
- Telophase: chromatids reach the poles, decondense and a nuclear envelope reforms around each set
- Produces two genetically identical daughter cells with the same number of chromosomes as the parent
- Important for growth, repair and replacement of cells, and for asexual reproduction
Full-mark answer
In prophase the chromosomes condense and become visible, each as two sister chromatids joined at a centromere, and the nuclear envelope breaks down. In metaphase the chromosomes line up along the equator of the cell, attached to spindle fibres by their centromeres. In anaphase the centromeres divide and the sister chromatids are pulled to opposite poles of the cell by the shortening spindle fibres. In telophase the chromatids reach the poles, decondense, and a nuclear envelope reforms around each set, followed by cytokinesis. Mitosis produces two daughter cells that are genetically identical to each other and to the parent cell, with the same number of chromosomes. This is important for growth, for repairing damaged tissue and replacing worn-out cells, and for asexual reproduction.
Examiner insight: 'Genetically identical' and 'same chromosome number' are two separate marks. Naming the stages without saying what happens to the chromosomes gains nothing.
AS 2 2019-style transport in plants question · 6 marks
Explain how water moves from the soil to the leaves of a plant, and explain the effect of increasing wind speed on the rate of transpiration.
Command word: Explain — how to answer itMark scheme — 6 creditworthy points
- Water enters root hair cells by osmosis, down a water potential gradient
- It crosses the root by the apoplast and symplast pathways to the xylem
- Water evaporates from mesophyll cell walls and diffuses out through the stomata - transpiration
- This lowers the water potential of the mesophyll, creating tension that pulls the column of water up the xylem
- Cohesion between water molecules (hydrogen bonds) keeps the column continuous; adhesion to the xylem walls also helps - the cohesion-tension theory
- Higher wind speed removes water vapour from around the stomata, maintaining a steeper water potential gradient, so transpiration rate increases
Full-mark answer
Water enters the root hair cells by osmosis because the soil solution has a higher water potential than the cell contents. It then crosses the root to the xylem, either through the cell walls in the apoplast pathway or through the cytoplasm in the symplast pathway. In the leaf, water evaporates from the walls of the mesophyll cells and diffuses out of the stomata as transpiration, which lowers the water potential of the mesophyll cells and creates tension in the xylem. This tension pulls the continuous column of water upwards; the column does not break because hydrogen bonding gives cohesion between the water molecules, and adhesion to the xylem walls also helps - this is the cohesion-tension theory. Increasing wind speed blows away the water vapour that would otherwise accumulate outside the stomata, so the water potential gradient between the leaf air spaces and the atmosphere stays steep and the rate of transpiration increases.
Examiner insight: Cohesion must be attributed to hydrogen bonds, and the wind mark needs the words 'water potential gradient' or 'diffusion gradient', not simply 'the water evaporates faster'.
AS 3 2019-style practical planning question · 6 marks
Describe how you would investigate the effect of temperature on the permeability of beetroot cell membranes, including how you would make the investigation valid and reliable.
Command word: Describe — how to answer itMark scheme — 6 creditworthy points
- Cut beetroot cylinders of the same length and diameter with a cork borer and rinse off surface pigment
- Place equal-sized pieces in equal volumes of water in a water bath at a range of temperatures (e.g. 20-70 degrees Celsius) for the same time
- Independent variable temperature; control volume of water, size of beetroot, time and beetroot variety
- Measure the absorbance / transmission of the solution with a colorimeter using a green filter
- Repeat at least three times at each temperature and calculate a mean
- Higher temperature increases membrane permeability because phospholipids gain kinetic energy and proteins denature, so more red pigment leaks out
Full-mark answer
I would use a cork borer to cut beetroot cylinders of identical length and diameter and rinse them to remove pigment released by cutting. One piece would be placed in a fixed volume of distilled water in a test tube and held in a water bath at a set temperature, for example 20, 30, 40, 50, 60 and 70 degrees Celsius, for the same length of time in each case. Temperature is the independent variable, so I would control the size of the beetroot piece, the volume of water, the time and the variety of beetroot. After the fixed time I would measure the absorbance of each solution in a colorimeter with a green filter, since more leaked pigment gives a higher absorbance. I would repeat each temperature at least three times and calculate a mean so that anomalies can be identified, making the results more reliable. Absorbance should increase with temperature because the phospholipids gain kinetic energy and move apart, and the membrane proteins denature, so the membrane becomes more permeable and more pigment leaks out.
Examiner insight: Marks are for named controlled variables and for the colorimeter, not for a general 'I would repeat it'. The explanation must mention both the phospholipids and the proteins.
These questions are written in the style of the CCEA GCE Biology (2016) papers and are not reproduced from any live paper. CCEA owns the copyright in its question papers and mark schemes — always download the official paper and mark scheme from CCEA and use these worked answers alongside them. BioCCEA is an independent study tool and is not endorsed by CCEA.
Download the official CCEA paper and mark schemePractise the AS 2019 paper in the app
These open BioCCEA with AS already selected, so you can sit questions in this paper's style and have them marked against the CCEA mark scheme.
Get your 2019 answers marked
Photograph a written answer from this paper and see it marked line by line in CCEA mark-scheme language, with the exact phrase you needed to earn each missing mark.