Biological Molecules
1. This question has 2 part(s).
1.1. Food items can often be spoiled if saprotrophic microorganisms such as mould fungi grow on them.
Describe how a saprotrophic fungus such as mould obtains its food.
1.2. A student uses this method to investigate ways of preventing peas from being spoiled.
Place three peas in each of three test tubes as shown in the diagram
Cover the peas in test tube A with water and keep at 37 °C
Cover the peas in test tube B with water and keep at 4 °C
Cover the peas in test tube C with vinegar, which is a weak acid, and keep at 37 °C
Leave the peas for 24 hours
The student observes the level of cloudiness of the solution to determine how spoiled the peas have become. The level of cloudiness can be used as a measure of fungal growth.
The table shows the student’s results.
Test tube | Conditions peas are kept in | Level of cloudiness |
|---|---|---|
A | Water at 37 °C | Very cloudy |
B | Water at 4 °C | Slightly cloudy |
C | Vinegar at 37 °C | No cloudiness |
(i) Suggest a problem with using the level of cloudiness of the solution to determine how spoiled the peas have become.
(1)
(ii) Explain the appearance of the peas in water at 4 °C.
(2)
(iii) Explain the appearance of the peas in vinegar at 37 °C.
(2)
Ai এর মাধ্যমে
১০ লক্ষ+ প্রশ্ন ডাটাবেজ
প্র্যাকটিস এর মাধ্যমে নিজেকে তৈরি করে ফেলো
উত্তর দিবে তোমার বই থেকে ও তোমার মত করে।
সারা দেশের শিক্ষার্থীদের মধ্যে নিজের অবস্থান যাচাই
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