The enzyme that breaks down starch into maltose in the small intestine is:
A. Salivary amylase
B. Maltase
C. Pancreatic amylase
D. Sucrase
Answer: Option C
Solution (By JKSSB Mock Tests)
Pancreatic amylase, secreted into the duodenum, continues starch digestion initiated by salivary amylase, producing maltose and dextrins. Maltase then breaks maltose to glucose. Sucrase acts on sucrose.
Explanation:
Peroxisomes are single-membrane organelles containing oxidative enzymes like catalase and urate oxidase. They break down fatty acids via β-oxidation and detoxify hydrogen peroxide. Lysosomes contain hydrolytic enzymes, mitochondria energy, Golgi packaging. Peroxisomes are abundant in liver and kidney cells.
In plant physiology, the 'Transpiration pull' theory, also known as the cohesion-tension theory, was proposed to explain the ascent of sap in tall trees. The key forces involved are:
A.Root pressure and capillarity
B.Active transport by xylem parenchyma
C.Osmotic pressure in the leaves
D.Cohesion between water molecules, adhesion to xylem walls, and tension created by transpiration
Explanation:
The cohesion-tension theory, primarily proposed by Dixon and Joly (and later supported by Denison), is the most widely accepted mechanism for the ascent of sap in tall trees. It relies on the physical properties of water. Transpiration from the leaves creates a negative pressure (tension) in the xylem. This tension pulls the water column upwards. The water column remains unbroken due to the high cohesive force between water molecules (hydrogen bonding) and the adhesive force of water to the hydrophilic walls of the xylem vessels and tracheids. This creates a continuous, passive pull from the top.
Consider statements about bryophytes: 1. They are called amphibians of the plant kingdom. 2. They possess vascular tissues. 3. They require water for fertilization. Which are correct?
Explanation:
Bryophytes are termed amphibians of the plant kingdom because they live on land but require water for the swimming of male gametes to reach the egg during fertilization. They lack true vascular tissues (xylem and phloem), which first appear in pteridophytes. Therefore, statements 1 and 3 are correct, but statement 2 is false.
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