neco model questions vol1 2020 biology | Practical

Prepare for your exams with neco model questions vol1 questions? Reviewing past/model questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2020 biology (Practical) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1 View Details
You are given a prepared slide of an onion (Allium cepa) epidermal peel stained with iodine. Using a compound microscope at 400×, answer the following.
Question Parts
(a)
List three distinct cell structures that can be observed in the field of view and give one function for each.
(b)
Explain why the cell wall appears as a clear outline while the nucleus appears as a dark stained region.
(c)
Suggest two precautions that should be observed when preparing the slide to avoid artefacts.
Detailed Essay Solution & Marking Scheme Available

Get the step-by-step mathematical proofs, key points required by examiners, and a comprehensive breakdown from our AI Tutor.

Reveal Answer
Question 2 View Details
A group of students set up an experiment to determine the effect of colchicine on the mitotic index of onion root tip cells. Fresh onion bulbs were placed in two sets of beakers: (i) control (distilled water) and (ii) treatment (0.1 % colchicine solution). After 24 h, root tips of 1 cm length were harvested, fixed in Carnoy’s fixative, and prepared as squashes stained with aceto‑orcein. For each slide, 500 cells were counted and the number of cells in each phase of mitosis recorded as follows: Control: prophase 120, metaphase 80, anaphase 50, telophase 30. Colchicine: prophase 30, metaphase 300, anaphase 10, telophase 10. Answer the following.
Question Parts
(a)
Calculate the mitotic index for the control and colchicine‑treated samples.
(b)
Determine the percentage of cells in metaphase for each sample and comment on the effect of colchicine.
(c)
Identify two sources of error that could affect the reliability of the mitotic index obtained.
(d)
Propose one improvement to the experimental procedure to reduce one of the errors identified in (c).
Detailed Essay Solution & Marking Scheme Available

Get the step-by-step mathematical proofs, key points required by examiners, and a comprehensive breakdown from our AI Tutor.

Reveal Answer
Question 3 View Details
A student is determining the carbohydrate content of an unknown food sample using the dinitrosalicylic acid (DNS) colourimetric method. The procedure involves preparing standard glucose solutions, measuring their absorbance at 540 nm, plotting a calibration curve and then analysing the unknown sample. The data obtained are shown in the table below. | Standard glucose concentration (g dL⁻¹) | Absorbance (A) | |------------------------------------------|----------------| | 0.20 | 0.12 | | 0.40 | 0.24 | | 0.60 | 0.36 | | 0.80 | 0.48 | The absorbance of the unknown sample solution was recorded as 0.30. The unknown food sample (2.5 g) was extracted with water and the extract was diluted to a final volume of 100 mL before the DNS assay. Answer the following:
Question Parts
(a)
Describe how you would prepare each of the four standard glucose solutions (0.20, 0.40, 0.60 and 0.80 g dL⁻¹).
(b)
Using the data in the table, plot a calibration curve of absorbance (y‑axis) against glucose concentration (x‑axis) and obtain the equation of the straight line (express the slope to two decimal places).
(c)
Calculate the concentration of glucose in the unknown sample solution using its absorbance (0.30).
(d)
Determine the percentage (w/w) of carbohydrate in the original food sample.
(e)
List two possible sources of error that could affect the accuracy of the result obtained.
Detailed Essay Solution & Marking Scheme Available

Get the step-by-step mathematical proofs, key points required by examiners, and a comprehensive breakdown from our AI Tutor.

Reveal Answer
Question 4 View Details
A group of students are investigating the effect of temperature on the rate of respiration in germinating beans using a closed‑system water‑displacement respirometer. The set‑up consists of a sealed container holding 10 germinating beans connected to an inverted graduated tube filled with water. The volume of gas displaced is recorded at 5‑minute intervals for three different water‑bath temperatures (20 °C, 30 °C and 40 °C). The data obtained are shown below. | Temperature (°C) | Time (min) | Volume of gas collected (mL) | |------------------|------------|------------------------------| | 20 | 5 | 12 | | 20 | 10 | 24 | | 30 | 5 | 18 | | 30 | 10 | 36 | | 40 | 5 | 30 | | 40 | 10 | 60 | Answer the following questions:
Question Parts
(a)
Outline the procedure for setting up the water‑displacement respirometer and recording the volume of gas produced.
(b)
Calculate the rate of respiration (in mL min⁻¹) for each temperature using the data provided.
Detailed Essay Solution & Marking Scheme Available

Get the step-by-step mathematical proofs, key points required by examiners, and a comprehensive breakdown from our AI Tutor.

Reveal Answer

Master the Exam!

You've seen a preview, but there are thousands more questions plus AI tutor to break down complex solutions.

Unlock Full Access Available for Android & Windows
Help others prepare! Share this practice hub:
Chat with Support