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- Question
Nucleus, the genetic material containing rounded body in each cell, was first discovered in 1831 by
Options- A. Robert Hooke
- B. Robert Brown
- C. Rudolf Virchow
- D. Theodore Schwann
- Correct Answer
- Robert Brown
- 1. Our skin, when exposed to excess sunlight, becomes dark. This is because our skin pigments called
Options- A. flavoxanthin
- B. melanin
- C. carotene
- D. Xanthophyll Discuss
- 2. Neurospora is used as genetic material because
Options- A. it has short life cycle of 10 days
- B. the product of single meiosis can be easily analysed
- C. meiotic products are linearly arranged in the form of ordered tetrads
- D. is a diploid fungus Discuss
- 3. Photosynthesis generally takes place in which parts of the plant?
Options- A. Leaf and other chloroplast bearing parts
- B. stem and leaf
- C. Roots and chloroplast bearing parts
- D. Bark and leaf Discuss
- 4. Radical vascular bundles are those in which
Options- A. xylem is surrounded by phloem
- B. phloem is surrounded by xylem
- C. xylem and phloem occur on the same radius
- D. xylem and phloem occur on the different radii Discuss
- 5. Outer covering of virus made up of protein is
Options- A. capsid
- B. coat
- C. virion
- D. viriod Discuss
- 6. Rain water helps to increase the ____ to some extent.
Options- A. phosphorous contents
- B. nitrogen contents
- C. calcium contents
- D. potash contents Discuss
- 7. Photosynthesis is a process
Options- A. reductive and exergonic
- B. reductive and catabolic
- C. reductive, endergonic and catabolic
- D. reductive, endergonic and anabolic Discuss
- 8. Radioactivity is a phenomenon of the spontaneous emission of
Options- A. protons (alpha particles)
- B. electrons (beta particles)
- C. gamma rays (short wave electromagnetic waves)
- D. All of the above Discuss
- 9. Prothrombin which helps in clotting of blood is released by
Options- A. lymphocytes
- B. erythrocytes
- C. monocytes
- D. blood platelets Discuss
- 10. Poison glands of snakes are homologous to
Options- A. electric organs of fishes
- B. stings of rays
- C. sebaceous glands of mammals
- D. salivary glands of vertebrates Discuss
Biology problems
Search Results
Correct Answer: melanin
Correct Answer: it has short life cycle of 10 days
Correct Answer: Leaf and other chloroplast bearing parts
Correct Answer: xylem and phloem occur on the different radii
Explanation:
In angiosperms the vascular bundles are mainly of three types (i) radial (ii) conjoint (iii) concentric.
(i) Radial : Presence of radial vascular bundles is the characteristic feature of roots. Those vascular bundles in which xylem and phloem are present on different radii are known as radial vascular bundles. In between xylem and phloem bundles parenchymatous cells are present.
(ii) Conjoint : In these vascular bundles xylem and phloem are present on the same radii. Conjoint vascular bundles may be collateral (phloem is present only outer to xylem) or bicollateral (phloem is present on both sides of xylem). If cambium is present between xylem and phloem then the vascular bundle is known as open, otherwise it is called closed.
(iii) Concentric : Those vascular bundles in which one type of vascular tissue is surrounded by another type are known as concentric vascular bundles. These bundles may be amphivasal or leptocentric(phloem is completely surrounded by xylem) or amphicribal or hardocentric (xylem is completely surrounded by phloem). Amphivasal bundles are found in Dracaena and Yucca. Amphicribal bundles are found in stamens of many dicots etc.
Correct Answer: capsid
Correct Answer: calcium contents
Correct Answer: reductive, endergonic and anabolic
Correct Answer: All of the above
Correct Answer: blood platelets
Correct Answer: salivary glands of vertebrates
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