Tag: cell division in embryo development
Questions Related to cell division in embryo development
Lipids are arranged within the membrane with ________.
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polar heads toward inner side and the hydrophobic tails toward outerside
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both heads and tails toward outerside
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heads toward outerside and tail towards inside
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both heads and tails toward innerside
The best material for the study of structure of cell membrane is _______.
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RBC of human
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liver cell
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kidney cell
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muscle cell
RBC (red blood cell) of the human is the best material for the study of structure of cell membrane. Chemical studies on the RBC cell membrane enabled the scientists to infer the possible structure of plasma membrane.
The three major components that constitute a typical cell are
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Plasma membrane, nucleus, organelles
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Organelles, nucleus, cytosol
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Cytosol, organelles, plasma membrane
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Plasma membrane, cytosol, nucleus
The main function of the cell membrane is to:
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Provide support
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Maintain the cell shape and size
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Regulate the flow of materials into and outside the cell
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All of the above
Which of the following statements is correct for the pollen tube
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It shows chemotactic movement
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It shows only tip growth
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It is composed of three non-cellular zones
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It shows radial cytoplasmic streaming
The movement of pollen tube towards embryosac though style is chemotactic as it secrets pectinases and other hydrolytic enzymes to create a passage for its entry into style .
If the diploid number of an angiospermic plant is 24, the number of chromosomes in the pollen grain, endosperm and integument will be
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12, 36, 12
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12, 24, 36
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12, 12, 36
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12, 36, 24
12, 36, 24; because pollen grains are haploid while endosperm has triploid chromosome number and integument is diploid in nature.
After penetrating stigmatic and styler tissues, the pollen tube usually grow down towards the egg because
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The egg cell attracts the pollen tube as they have dissimilar electric charge
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The filiform apparatus of synergids is believed to attract the pollen tube
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It has no other passage to follow
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It grows under control of nucleus
In porogamy, filiform apparatus of synergids secretes, some chemotropically active sunstances, which direct the pollen tube towards micropyle of ovule.
Intine of pollen grain is made of.
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Callose
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Pecto-cellulose
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Cellulose
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Fat-like sporopollenin
In amoeboid type of tapetum.
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The cells remain in situ
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The cells secrete chemicals for degeneration of middle layers
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The cells pass in between the middle layers
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The cells form plasmodium that passes in between pollen grain mother cells
This type of tapetum can be seen easily in Alisma, Butomus, Tradescantia, and Typha, etc. The tapetal cells fuse among themselves for forming a tapetal plasmodium. The protoplast of the fused tapetal cells then moves into the locule, where they surround the pollen mother cells or pollen grains. This protoplast movement into the locule is taking place during meiotic prophase.
Thus the correct answer is option D.
Wall of a mature pollen grain consists of.
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Ektexine and endexine
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Tapetum and endothecium
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Exine and intine
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Foot and baculate layer
The pollen wall actually is the multi-layered structure that includes an intine, which is composed mainly of polysaccharide, and an exine, which consists mainly of sporopollenin. The exine can be further divided into the sexine and nexine. Sexine is the single layer of bacula which is covered by a layer of the tectum.
So the correct answer is C.