MTG Foundation Course Book Class 7 Biology 2025, MCQ QUIZ, SOF Olympiad, NELAS, Olympiad Preparation

MTG Foundation Course Book Class 7 Biology 2025, MCQ QUIZ, SOF Olympiad, NELAS, Olympiad Preparation
Q 31 to Q 50 are LEVEL 2
Q 51 to Q 60 are LEVEL 3 (HOTS)
Here are the Explanations for Tough questions are included (to avoid extending the video)
08:36 Question 16 - Answer (d) Although nitrogen is present in abundance in the atmosphere, plants cannot use this free nitrogen directly. Plants obtain nitrogen either through fertilizers added into the soil or through certain nitrogen fixing bacteria (e.g., Rhizobium bacteria) which convert atmospheric free N2 into soluble nitrogenous compounds and release them into the soil.
15:19 Question 31 - Answer (b) The given plant is undergoing the process of photosynthesis. Rate of photosynthesis is directly affected by the intensity of light, amount of water and concentration of CO2 as these are the raw materials of photosynthesis. Amount of fertilizer and concentration of O2 will not have a direct effect on the rate of photosynthesis.
15:47 Question 32 - Answer (a) When a potted plant is a kept in a dark place for 2-3 days, it gets destarched. This is because starch stored in the plant gets consumed during the process of respiration. Moreover, no new starch formation takes place due to absence of photosynthesis. When a leaf is plucked from this plant and is tested for the presence of starch by carrying out iodine-test, the leaf remains yellow-brown in colour indicating the absence of starch.
16:43 Question 34 - Answer (b) In the given experimental set-up, the bubbles produced in the water within test tube are mainly of oxygen gas. Oxygen gas gets collected by the downward displacement of water in the test tube. This experiment is used to demonstrate that oxygen gas is released during photosynthesis.
17:40 Question 36 - Answer (d) Rate of photosynthesis increases with i.e., approximately 40°C, Above this temperature, an increase in temperature upto a certain point there is a decrease in the rate of photosynthesis.
18:10 Question 37 - Answer (c) Only the disc 2 in the figure shows positive test for starch. It is because it contains food by photosynthesis. The discs 1 and 3 do chlorophyll and is receiving sunlight to synthesize not contain chlorophyll, thus, will not perform photosynthesis. Disc 4 is destarched, and is covered by black paper, it contains chlorophyll but is not receiving sunlight to carry out the process of photosynthesis hence, cannot synthesize starch.
18:38 Question 38 - Answer (c) Cuscuta shows parasitic mode of nutrition. It lives as parasite on other plant called host. Mosquitoes are also parasites. They obtain nutrition by sucking the blood of host (human), thereby showing parasitic mode of nutrition. Yeasts lack chlorophyll. They cannot synthesize their own food. They obtain nutrition by feeding on dead and decaying organic matter. Hence, they show saprotrophic mode of nutrition.
20:00 Question 41 - Answer (a) The opening and closing of stomata is carried out by guard cells. In sunlight (daytime), water from surrounding cells diffuses into the guard cells. The guard cells become turgid (swell) by the accumulation of water, their outer thin walls bulge out and the inner thick walls are drawn apart. The stomatal pore between the two guard cells widens, making the stoma open. When there is no sunlight (during night), water diffuses out of the guard cells. The guard cells become flaccid (shrink), their inner thick walls become straight and the stoma gets closed.
23:52 Question 49 - Answer (b) Chlorophyll pigment does not absorb green light, rather it reflects and transmits the green light. That is why leaves appear green in colour. Chlorophyll absorbs blue and red lights which are most effective in photosynthesis.
24:50 Question 51 - Answer (c) According to the given flow chart, P is Elodea as it is an autotrophic plant, Qis Cuscuta is a parasitic plant that does not possess chlorophyll and cannot make its own food by photosynthesis. R is Rhizopus as it shows saprophytic nutrition and S is Gambusia as it shows heterotrophic mode of nutrition only.
25:18 Question 52 - Answer (d) (d): Rafflesia in group I is a parasitic plant whereas Nepenthes and Drosera are insectivorous plants. Utricularia in group II is an insectivorous plants. Dionaea in group III is an insectivorous plant whereas Cuscuta and Hydnora are parasitic plant whereas. Hibiscus and Petunia are flowering plants.
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