Home BIOLOGY Transport Biology​​ Practical Questions And Answers

Transport Biology​​ Practical Questions And Answers

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Transport Biology​​ Practical Questions And Answers

Transport Biology​​ Practical Questions And Answers

BIOLOGY PRACTICAL O’LEVEL Transport | Transport Biology​​ Practical | Transport Biology​​ Practical | Transport Questions With Answers | Transport

Format

Until 2008, NECTA biology practicals contained three questions. Question 1 was required, and was a food test. Students then chose to answer either question 2 or question 3.

One of these questions was usually classification. The format changed in 2008. Now, the practical contains two questions, and both are required.

Food test and classification remain the most common questions, but sometimes only one of these two topics is on a given exam.

The second question may cover one of a variety of topics, including respiration, transport, coordination, photosynthesis, and movement.

Each question is worth 25 marks.

Common Practicals

<> Food test:​​ students must test a solution for starch, sugars, fats, and protein

<> Classification:​​ students must name and classify specimens, then answer questions about their characteristics

<> Respiration:​​ students use lime water to test air from the lungs for carbon dioxide

<> Transport:​​ students investigate osmosis by placing leaf petioles or pieces of raw potato in solutions of different solute concentrations

<> Photosynthesis:​​ students test a variegated leaf for starch to prove that chlorophyll is necessary for photosynthesis

<>Coordination:​​ students look at themselves in the mirror and answer questions about the sense organs they see

Note:​​ These are the most common practicals, but they are not necessarily the only practicals that can occur on the national exam. Biology practicals frequently change, and it is possible that a given exam will contain a new kind of question. Look through past NECTA practicals yourself to get an idea of the kind of questions that can occur

Transport

The purpose of this practical is to investigate osmosis by observing the changes in a leaf petiole placed in a hypotonic solution (water) and a hypertonic solution (water containing salt or sugar).

This section contains the following:
  • Materials
  • Sample practical with solutions

1. Materials

The petiole is the stalk which attaches a leaf to a branch. The papaya leaf petioles in this practical should be soft petioles from young leaves, not stiff petioles from older leaves.

Cut the petioles into pieces, and give each student two pieces of about 6 cm in length. Cylinders cut from a raw potato may be used instead of petioles.

The hypertonic solution may be made with by mixing either salt or sugar with water. The hypotonic solution is tap water.

2. Sample practical with solutions

Practical​​ 01

A form four student was interested to investigate osmosis phenomenon and decided to set the experiment as shown in figure 7 below

Study this figure and answer the questions that follow.

  1. Which solution has a higher concentration of free water​​ molecules?
  2. Which solution has high solute​​ concentration
  3. In which direction will osmosis​​ occur?
  4. What does the semi – permeable membrane corresponds to within an animal​​ cell?
  5. What is​​ osmosis?
  6. Name five (5) processed in living things that depend on​​ osmosis
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Solution

Solution which as a higher concentration of free water molecules is solution​​ B.

Solution which has high solute concentration is solution​​ A

Osmosis will occur in this way; water molecules will move from solution B through semi permeable membrane towards solution​​ A

The semi-permeable membrane correspond to plasma membrane within an animal​​ cell

Osmosis​​ refers​​ to​​ the​​ movement of​​ solvent​​ (water)​​ from​​ the​​ region​​ of​​ its​​ low​​ concentration​​ to​​ the​​ region​​ of​​ its high concentration through semi – permeable​​ membrane.

OR

Osmosis is the movement of a solvent across semi- permeable membrane toward a higher concentration of solute.

Five (5) process in living things that depends on osmosis​​ are:-

  • Active​​ transport
  • Passive​​ transport
  • Plasmolysis
  • Osmotic​​ pressure
  • Endocytosis
  • Osmotic​​ gradient
  • Oxocytosis

Practical​​ 02

1. You are provided with a beaker, tea bag and hot water. Carry out the following experiment. Pour about 100cm3​​ off hot water into the beaker.

2. Put the tea bag into the beaker containing hot water. Observe carefully the experiment for a few minutes.

a.(i)​​ What happened to the tea bag when it was put in hot water?

(ii)​​ Explain why the changes you observed occurred?

b.(i)​​ What do you think was the aim of the experiment?

(ii)​​ Draw a conclusion from the experiment

c. (i)​​ Name the physiological process investigated in this experiment

Define the process named in (c) (i)​​ above

What is the importance of this process in​​ nature?
Solution

(i)​​ When tea bag was put in hot water, water rushed (entered) the tea bag through Osmosis process, after attaining​​ equilibrium​​ water​​ soluble​​ ingredients​​ (chemicals)​​ from​​ the​​ tea​​ bad​​ started​​ to​​ go​​ out​​ (diffuses)​​ slowly​​ into the beaker containing hot water and changes the color of hot water slowly from clear (colorless) to brown color through diffusion​​ process.

(ii)​​ The above change a (i) occurred due to occurrence of both diffusion and osmosis. Osmosis process is when hot water molecules entered (moved) into a tea bag through selectively permeable membrane (tea bag material), and the diffusion process is when aqueous solutes (soluble chemical ingredients) moved out (diffuses) from the tea bag into the beaker containing hot water and finally becomes brown in color.

(i)​​ Aim of the experiment was demonstrate both Osmosis and diffusion​​ processes.

(ii)​​ In conclusion, tea bag acted like a cell membrane because it controlled what went in and out just like a cell osmosis and diffusion occurred when tea color left the bag and water entered the bag.

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It also acted like a cell membrane by keeping some things in likes the tea leaves.

(i)​​ The physiological process investigated in this was either Diffusion or​​ Osmosis.

Diffusion​​ is the movement of substance from area of higher concentration to area of lower concentration.​​

Osmosis​​ is the movement of water molecules through or across semi permeable membrane from where they are in high concentration to where they are in low concentration in order to reach​​ equilibrium.

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Importance of diffusion in​​ nature

Diffusion is a process in which material spreads throughout a liquid or gas, it is important to living things as it explains how useful materials and waste products can move into and out of cells. Digested food molecules (amino acids, glucose) move down a concentration gradient from the intestine to the blood.

Diffusion allows the exchange of substances; the entry of oxygen, proteins etc. into the cell and the removal of waste substances.

Importance of Osmosis in​​ nature

Osmosis is a natural physical process in which water molecules moves across a selectively permeable membrane from area of high concentration to an area of low concentration so as to maintain equilibrium.

Plants need osmosis because, through osmosis they their water. So plant cells maintain their water content despite the loss of water to the air that is constantly occurring.

Osmosis provides turgidity to the softer tissues and is therefore, essential for their mechanical support. It also controls the absorption of water by root hairs from the soil etc.

Practical​​ 03

In an experiment to find the composition of blood, 5cm3 of fresh blood from a rabbit was centrifuged and the result was as shown below

Most plentiful in​​ B

Least plentiful in​​ B

c)Arrange in increasing order the substances present in​​ B

Solution

Practical​​ 04

You are provided with solid sample C and distilled water. Fill the beaker with distilled water using a spatula slowly put a small portion of the solid sample C in a beaker of water and observe the changes in the mixture for 5mn then answer the question that follows.

Solution

Practical​​ 05

Solution

Osmosis

Is the movement of water molecules from high concentration of water molecules to low concentration of water molecules.

Practical​​ 06

You have been provided with specimen X and two solutions SI and S2. Using razor blade or scalpel, cut 6cm long petiole from Specimen X. Use this same piece of petiole in all 3 stages of the experiment described below.

Stage I:

Using razor blade or scalpel, spirit the piece of petiole from Specimen X longitudinally up to its length so as to produce 4 strips on one end of the specimen, while the other end remains intact as shown in the diagram.

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Stage II

Dip the piece of petiole in solution S2 for about 10 minutes. Remove it from the solution, observe and touch it gently to feel it’s hardness or softness.

Stage III

Dip the petiole in S3 for about 10 minutes. Remove it from the solution, observe and touch it gently to feel its hardness or softness.

Record your observations and explanations for Stage II and stage III of the experiment as shown in the​​ table.

Stage of Experiment
Observation
Explanation

Stage II

Stage III

  1. What was the aim of the​​ experiment
  2. Give brief comments on the concentrated of solution S2 and​​ S3
  3. Why is the biological process demonstrated by the above experiment important to​​ plant?
  4. Define the process demonstrated by the above​​ experiment
  5. Explain what happen to the cells of the petioles in Stage II and Stage III. Illustrate your​​ answer.
Solution
a.

Stage of Experiment

Observation

Explanation

Stage II

The piece of petiole becomes

soft

It shrinks due to loss of water

Stage III

The piece of petiole becomes hard and strong

It absorbs water and become turgid

To demonstrate the process of​​ Osmosis

– The solution of S2 is hypertonic (too concentrated) compound to cell sap of the leaf petiole that is why the petioles lose water and become​​ plasmelysed.

– The solution S3 is hypotonic (less concentrated) compared to the cell sap of the leaf petiole that is why the petiole absorbs water and become turgid.

i.​​ It is important as it enables plant roots to absorb water and dissolved mineral salt from​​ the soil also give strength to the offers support​​ plant

ii.​​ Allows opening of stomata hence facilitate gaseous exchange.

Osmosis is the movement of water Transpiration molecules from lowly concentrated solution to​​ highly concentrated solution through semi- permeable​​ membrane.

In stage IT the petiole loses water, shrinks and become​​ plasmolysed

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