Unit 1

Which of the following is not an autotroph?

• Mint

• Grass

• Cuscuta

• Ferns

Answer explanation

Cuscuta is not an autotroph because it does not have chlorophyll and depends on other plants for nutrition through a parasitic mode of life.

What fills in the empty blanks:

6CO₂ + 6H₂O _chlorophyll---- ^sunlight C_--H_--O + 6O_--

• 6 , 12, 24, 6

• 8, 4, 2, 12

• 6, 12, 6, 12

• 6, 12, 6, 2

Answer explanation

Carbon dioxide + Water → (in presence of sunlight and chlorophyll) → Glucose + Oxygen

🧪 Chemical Equation:

6CO₂+6H₂O (sunlight, chlorophyll) → C₆H₁₂O₆+6O₂ + 6H₂O

In Photosynthesis, carbon dioxide is reduced to

• carbon monoxide

• carbonate

• carbohydrate

• carboxylic acid

Answer explanation

In photosynthesis, carbon dioxide (CO₂) is reduced to form carbohydrates (like glucose).
This means CO₂ gains hydrogen and electrons (from water using sunlight energy) and becomes sugar.
This process happens in the chloroplasts using sunlight, water, and CO₂.

👉 Example:

6CO2+6H2O→sunlightC6H12O6+6O26CO_2 + 6H_2O \xrightarrow{\text{sunlight}} C_6H_{12}O_6 + 6O_26CO2​+6H2​Osunlight​C6​H12​O6​+6O2​

CO₂ is reduced → Glucose is formed.

Which of the following give dark blue color with iodine

• Glucose

• Starch

• Protein

• Fats

Answer explanation

• When iodine solution (brown in color) is added to starch, it turns dark blue or blue-black.

• This happens because iodine molecules fit into the helical structure of amylose, a component of starch.

• This interaction causes a chemical complex that reflects blue light — hence the blue-black color.

• Starch + Iodine → Blue-black color

• This is a common test to check the presence of starch in food items.

______ is the most essential element for the synthesis of proteins

• Magnesium

• Phosphorus

• Nitrogen

• Iron

Answer explanation

1. Proteins are made of amino acids, and each amino acid contains:

   • Carbon (C)

   • Hydrogen (H)

   • Oxygen (O)

   • And Nitrogen (N) ❗

2. Nitrogen is a key part of the amino group (-NH₂) in amino acids.
   Without nitrogen, the body (or plant) cannot build amino acids, and therefore, cannot make proteins.

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🌱 In Plants:

• Plants absorb nitrogen from the soil in the form of nitrates or ammonium ions.

• They use it to make amino acids, which are then used to build proteins needed for growth and development.

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🧾 Summary:

• Proteins cannot be made without nitrogen.

• Hence, nitrogen is essential for protein synthesis.

Peristaltic movements are observed in

• Oesophagus

• Small Intestine

• Large intestine

• All of the above

Answer explanation

Peristaltic movements are wave-like muscle contractions that push food through the digestive tract.

They occur in:

• Oesophagus – to move food from mouth to stomach.

• Small Intestine – to mix food with enzymes and absorb nutrients.

• Large Intestine – to move waste and absorb water.

These movements are automatic and essential for digestion.

Gastric glands are located in the

• Walls of Intestine

• Walls of Stomach

• Walls of liver

• Under the tongue

Answer explanation

Gastric glands are present in the stomach walls and play an important role in digesting food, especially proteins.

___________ is the longest part of the alimentary canal

• Stomach

• Small Intestine

• Larg intestine

• Oesophagus

Answer explanation

Small intestine is the longest part of the alimentary canal and plays a key role in digestion and absorption of nutrients.

which of the following animals has a shorter small intestine?

• cow

• elephant

• Rhino

• Leopard

Answer explanation

Leopard, being a carnivore, has a shorter small intestine because meat is easy to digest and doesn't require a long digestive tract.

Which of the following enzyme needs acidic medium to work?

• Trypsin

• Pepsin

• Lipase

• Amylase

Answer explanation

Pepsin needs an acidic medium to get activated and digest proteins. That’s why it works only in the stomach, where HCl is present.