Q: A student placed 3 cm potato strips in 0.0M, 0.2M, and 0.6M sucrose solutions for 30 minutes. The 0.2M strip remained rigid. What does this indicate?
Model answer:
The 0.2M sucrose solution has the same water potential as the potato cells. Therefore, there is no net movement of water into or out of the cells, so the strips maintain original turgidity.
A student tested a solution X. Benedict’s test remained blue. Iodine test turned blue-black. Biuret test remained blue. Ethanol emulsion test remained clear. Identify X.
To get the exact marking points for the specific questions, you should refer to the official Examiner's Report for 2020. You can find this on the CAIE (Cambridge Assessment International Education) official website or through your school's exam officer.
Why use the Examiner's Report instead of a simple answer key? It explains why students lost marks. For example, it might say, "Many candidates failed to mention that the Benedict's solution needed to be heated." This provides insight that a simple "Answer: Glucose" list cannot.
Good luck with your revision! Remember: Practical Biology is about accuracy and clarity, not just memorization.
The Investigation of Photosynthesis in Elodea Plants
It was a sunny day in May 2020, and biology students from a local school were heading to the laboratory to conduct their O-level biology practical exam. The topic of the practical was the investigation of photosynthesis in Elodea plants.
The students had been preparing for weeks, revising the concepts of photosynthesis, and practicing their experimental skills. As they entered the laboratory, they were greeted by the familiar sight of Elodea plants, microscopes, and various equipment needed for the experiment.
The task was to investigate how light intensity affects the rate of photosynthesis in Elodea plants. The students were required to design and conduct an experiment to measure the effect of different light intensities on the rate of photosynthesis.
The Experiment
Each student set up their own experiment, using a similar method:
The Results
As the students collected their data, they began to notice a trend. The closer the lamp was to the plant, the more oxygen was produced. This made sense, as higher light intensities provide more energy for photosynthesis to occur. o level biology practical 2020 answers
When they plotted their results on a graph, they saw a positive correlation between light intensity and the rate of photosynthesis. However, they also noticed that at very high light intensities, the rate of photosynthesis seemed to level off.
The Answers
Now, let's imagine some possible answers to common questions that might be asked in the O-level biology practical exam:
Answer: To investigate how light intensity affects the rate of photosynthesis in Elodea plants.
Answer: As light intensity increases, the rate of photosynthesis also increases, but may level off at very high light intensities.
Answer: Elodea plants are used as a model organism to investigate photosynthesis. They produce oxygen as a byproduct of photosynthesis, which can be measured and used to estimate the rate of photosynthesis.
Answer: By repeating the experiment multiple times, using similar equipment and methods, and controlling variables such as temperature and light source.
Of course, these are just sample answers, and actual answers may vary depending on the specific questions and requirements of the exam.
The 2020 O Level Biology Practical (Syllabus 5090 and 6093) centered on testing students' ability to execute experimental procedures, record precise observations, and interpret biological data. Key experiments included investigating glucose concentration in "urine" samples and analyzing the transverse section of a lime fruit. 2020 Practical Paper Highlights & Answers
The examination was divided into investigative tasks that required both manual dexterity and theoretical application. Question 1: Glucose Concentration Analysis
In this experiment, students were tasked with estimating the concentration of glucose in five different samples (labeled A-E) representing "urine."
Methodology: Students used the Benedict’s test, recording the time taken for the first color change to occur. Sample Results:
Sample B typically showed the shortest time (e.g., 26 seconds), indicating the highest glucose concentration (approx. Q: A student placed 3 cm potato strips in 0
Sample D often remained blue or took over 120 seconds, representing a concentration of
Key Table Requirements: Answers had to include correct headings (e.g., "Time taken for color change / s") and consistent units. Question 2: Biological Drawing and Magnification
This section focused on the Transverse Section (T.S.) of a lime fruit.
Drawing Criteria: Successful diagrams occupied at least half the provided space, used clean, continuous lines (no shading), and correctly detailed the juicy pulp and sectors.
Calculation: Students calculated the magnification using the formula:
Magnification=Length of drawingLength of actual specimenMagnification equals the fraction with numerator Length of drawing and denominator Length of actual specimen end-fraction Answers were expected to be given to 2 significant figures.
2020 O-Level Biology Practical Guide | PDF | Flowers - Scribd
This exam focused on enzyme activity and food tests, specifically using the Benedict’s test to identify unknown glucose concentrations. Glucose Concentration Investigation:
Procedure: You were required to perform serial dilutions and record the time taken for Benedict's solution to change from blue to a "first sign" of color (e.g., green, yellow, or brick-red).
Data Analysis: Faster color changes indicated higher glucose concentrations. For example, a sample that changed color in 26 seconds was estimated at 0.95 g/dm³, while one taking 42 seconds was lower at 0.45 g/dm³.
Graphing: Expected graphs plotted "Time taken for color change" against "Concentration of glucose". Drawing & Identification:
Specimen Drawing: A transverse section of a lime fruit. Marks were awarded for clear, continuous lines, occupying at least half the provided space, and realistic details like the juicy pulp and green skin.
Magnification: Calculations required measuring the realistic length of the specimen and including proper units (cm/mm). 2. 5090 Alternative to Practical (Paper 6) A student tested a solution X
Common topics in the 5090 series included the effects of temperature on pigments and plant tissue reactions.
Beetroot Pigment Investigation: You investigated how temperature affects the release of red pigment from beetroot cells. Higher temperatures generally cause more cell membrane damage, leading to a darker red color in the surrounding water.
Enzyme Reactions in Fruits: One version featured banana slices to observe browning caused by enzymes reacting with oxygen when exposed to air. 3. Key Practical Skills & Tips
Independent vs. Dependent Variables: In the 2020 papers, the independent variable was often temperature or concentration, while the dependent variable was time (e.g., time for color change).
Accuracy: Always record time to the nearest second and use a measuring cylinder for precise volumes.
Table Construction: Ensure your table has clear headings with units separated by a slash (e.g., Time / s) and that the independent variable is in the first column.
To refine your study, you can download official mark schemes and examiner reports from platforms like PapaCambridge or Save My Exams.
O Level Biology Practical 2020 Answers: A Comprehensive Guide
The O Level Biology Practical 2020 exam is a crucial assessment for students pursuing biology at the ordinary level. The practical component of the exam evaluates students' ability to apply theoretical knowledge in a hands-on setting, focusing on their skills in observation, measurement, and data analysis. Here, we provide a detailed overview and answers to the O Level Biology Practical 2020 exam, helping students understand the expected outcomes and improve their performance.
Understanding the O Level Biology Practical Exam
The O Level Biology Practical exam is designed to test students' ability to:
The exam typically consists of two to three experiments or investigations, each assessing different aspects of biological inquiry.
O Level Biology Practical 2020: Experiment 1 - Investigating the Effect of pH on Enzyme Activity
Checklist of what the 2020 mark scheme awarded marks for:
Specific 2020 Terminological Requirement: Students who labeled the central clear area as "air bubble" lost marks. The correct label is "vacuole" or "tonoplast" .