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Explore Class 12 Biology past and model questions by chapter, year, marks and question type.
178 questions found
What are called the two nuclei present at the end of the pollen tube?
Sperm and ovum
Generative nucleus and stigma
Tube nucleus and sperm
Tube nucleus and generative nucleus
Which of the following cells has cytoplasm but no nucleus in mature stage?
Vessel
Sieve tube
Companion cell
Tracheid
Two cells A and B are contiguous as shown in the diagram. Cell A has osmotic pressure 12 atm, turgor pressure 9 atm, and diffusion pressure deficit 5 atm. Cell B has osmotic pressure 10 atm, turgor pressure 5 atm, and diffusion pressure deficit 7 atm. Which one of the following results will happen?
No movement of water
Equilibrium between the two cells A and B
Movement of water from cell A to B
Movement of water from cell B to A
Which of the following is not a part of methods of hybridisation?
Tagging
PCR
Emasculation
Bagging
What is ascent of sap? Describe how transpiration pull, cohesive and adhesive properties cause ascent of sap in tall trees.
Explain briefly about the double helix structure of DNA with necessary diagram.
Draw a longitudinal section of a pistil showing pollen germination. Explain the events on the embryo-sac during the process of fertilization.
“DNA recombinant technology is our friend as well as foes”, comment upon this statement with reasons.
Which structure is found in the blastula stage?
Blastopore
Archenteron
Blastocoel
Neurula
Geneticists have found that not all traits show simple dominant-recessive relationship. Justify this statement by describing incomplete dominance and codominance with suitable illustrations
Haversian system is the diagnostic feature of bones. Which of the following animal has this system present?
Mammals
Reptiles
Aves
Amphibians
During tissue respiration, CO₂ formed in the tissues is highly toxic to the body. How would the blood expel CO₂ from tissues to the lungs?
In the form of oxyhaemoglobin
In the form of ethyl alcohol
In the form of bicarbonates
In the form of glucose
Which part of human body the organ of Corti is present?
Retina
Internal ear
Middle ear
Nasal chamber
A person is suffering from respiratory disorder. What would be the possible cause of COPD?
Using caffeine
Exposure to pollutants
Inhalation of tranquilizers
Exposure to narcotics
How would you detect a baby to be born having genetic defect? Name the technique.
Test-tube baby
In-Vitro Fertilization
Organ transplantation
Amniocentesis
Draw a labelled diagram of a neuron. How would you differentiate medullated and non-medullated neuron?
Describe the process of spermatogenesis in animals with diagram.
Label A and B.
Mention any two hormones released by A and B with their one function.
How would you elaborate the phenomenon of ultra-filtration in process of urine formation in human body?