Which of the following is a characteristic of living organisms but NOT of non-living objects?
A. Occurrence in nature
B. Ability to respond to stimuli
C. Possession of mass
D. Increase in size
Answer: Option B
Solution (By JKSSB Mock Tests)
Living organisms exhibit irritability, i.e., they detect and respond to changes in their environment. Non-living objects can increase in size (e.g., crystal growth), possess mass, and occur in nature, but they lack consciousness and the ability to respond to stimuli. Thus, responsiveness is a defining property of life.
Explanation:
Meiosis I features crossing over (prophase I) and independent assortment of homologous chromosomes, creating genetic diversity in gametes. Mitosis produces identical cells, binary fission is asexual, fragmentation is a form of asexual reproduction.
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.
Consider statements about biotechnology: 1. PCR can amplify a specific DNA sequence. 2. Gel electrophoresis separates DNA fragments by size. 3. Restriction enzymes join DNA fragments. Which are correct?
Explanation:
Polymerase Chain Reaction (PCR) is a powerful technique used to exponentially amplify a specific segment of DNA using primers and a thermostable DNA polymerase. Gel electrophoresis is a method used to separate DNA, RNA, or protein molecules based on their size and charge by applying an electric field through a gel matrix. Restriction enzymes are molecular scissors that cut DNA at specific sequences; DNA ligase is the enzyme that joins DNA fragments together. Thus, statements 1 and 2 are correct.
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