All Free Biology MCQs with Answers
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19844 questions · page 681 of 1985
6801. Tonoplast is important for:
- A. Oxidative phosphorylation
- B. Transporting ions against concentration gradients
- C. Providing rigidity to the structure
- D. Cell division
Explanation: Tonoplast is the membrane surrounding the vacoule. The vacuole helps in maintaining cell volume and cell turgor; the regulation of cytoplasmic ions and pH. The tonoplast helps in the transpot of ion and minerals against the concentration gradient into the vacuole utilizing energy in the form of ATP.
Correct answer: Transporting ions against concentration gradients6802. Both cilium and flagellum emerge from centriole like structure which is called:
- A. Basal granules
- B. Basal lamina
- C. Basal bodies
- D. Basal ganglion
Explanation: Basal bodies are modified centrioles that give rise to cilia and flagella.
Correct answer: Basal bodies6803. Based on the position of the centromere, the chromosomes are classified into how many types?
- A. 1
- B. 2
- C. 3
- D. 4
Explanation: The chromosomes are called telocentric, acrocentric, sub metacentric and metacentric depending upon the location of centromere between the middle and tip of the chromosomes.
Correct answer: 46804. Nucleus may be ........ or .......... in shape.
- A. Irregular, spherical
- B. Rectangular, spherical
- C. Elongated, spherical
- D. Ellipsoidal, square
Explanation: Most of the nuclei are spherical in shape, however nuclei of certain cells (like various types of WBCs.) have irregular shapes e.g. the nucleus of neutrophils is two to five lobed and that ofEsinophil and Basophil is bilobed
Correct answer: Irregular, spherical6805. The example of polynucleate cells is:
- A. Smooth muscle cells
- B. Striated muscle cells
- C. Striped muscle cells
- D. Skeletal muscle cells
Explanation: Skeletal muscle cells are highly elongated and become unwieldy to be controlled by a single nucleus; thus contain many nuclei per cell.
Correct answer: Skeletal muscle cells6806. In non-dividing phase nucleus contains _ and soluble sap called _ respectively.
- A. Chromatin network, nucleoplasm
- B. Chromosomes, nucleoplasm
- C. Nucleoplasm, chromatin network
- D. Chromatin network, cytoplasm
Explanation: In non-dividing cell (interphase) DNA of chromosomes have been decondensed and uncoiled. In this form it is called chromatin network. However, during cell division through recondensation and recoiling this chromatin network is converted into discrete structures called chromosomes. Chromatin network is suspended in a fluid substance called nucleoplasm.
Correct answer: Chromatin network, nucleoplasm6807. The hereditary material is in the form of chromosomes, which control:
- A. Reproductive activities of the cell
- B. Somatic activities of the cell
- C. All activities of the cell
- D. Physiological activities of the cell
Explanation: All activities of a cell are controlled by its genetic material or DNA, through the genes; called units of inheritance. Genes are located on chromosomes.
Correct answer: All activities of the cell6808. The membrane that separates the nuclear material from the cytoplasm is:
- A. Plasmalemma
- B. Cytoplasmic membrane
- C. Plasma membrane
- D. Nuclear membrane
Explanation: In eukaryotic cells nuclear membrane or nuclear envelope separates the nuclear material from cytoplasm. It is double membrane having pores inside it.
Correct answer: Nuclear membrane6809. The outer and inner nuclear membranes are continuous at certain points, resulting in the formation of:
- A. Endoplasmic reticulum
- B. Nucleolus
- C. Nuclear pores
- D. Chromosomes
Explanation: Pores are formed by the fusion of outer and inner nuclear membranes at certain points which are source of communication between cytoplasm and nucleus.
Correct answer: Nuclear pores6810. The exchange of material between the nucleus and the cytoplasm is carried out through:
- A. Endoplasmic reticulum
- B. Nuclear pores
- C. Vacuoles
- D. Nuclear envelope
Explanation: Nuclear pores are source of communication between nucleus and cytoplasm. Cytoplasm is the centre of metabolism for cell and each metabolic activity is controlled by genetic information located on chromosomes in the nucleus
Correct answer: Nuclear pores