- Xylem contains tracheids, vessels, xylem parenchyma and xylem fibre.
- Tracheids: They are elongated, tubular dead cells with tapering end walls.
- Vessels: These are also known as trachea. They are elongated, tubular dead cells. They are joined to each other by end to end forming a continuous pipe. The cells are thick and lignified.
- Xylem parenchyma: They are also called wood parenchyma. This is the only living tissue of xylem.
- Xylem fibre: They are dead cells with thick walled fibre.
- Phloem consists of sieve tubes, companion cells, phloem parenchyma and phloem fibres.
- Sieve tubes: These are elongated, tubular living cells arranged in a row, with their perforated end walls forming a sieve. They are non-nucleated. Their protoplasm are inter-connected through sieve plates. They possess vacuoles.
- Companion cell: They are elongated, lens-shaped cells containing dense cytoplasm and prominent nuclei. These cells maintain connection with sieve cells through pits.
- Phloem parenchyma: They are living thin walled parenchyma cells.
- Phloem fibre: They are also known as bast fibre. They are elongated fibre like sclerenchymatous dead cells with thick walls containing pits and interlocked ends. Phloem fibre are the only dead cells in phloem.
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Is this a true or false question?
The <em>S. salivarius</em> is chosen because it the predominant gram positive bacteria that colonizes the oral cavity shortly after birth.
<h3>What is PCR?</h3>
Polymerase chain reaction(PCR) test is a type of test that is used to identify a particular deoxyribonucleic acid of an organism.
<em>Streptococcus salivarius</em> cannot be cultured especially when the test sample is contaminated with other body normal flora.
The steps of PCR testing include the following:
- Annealing Primer to Target Sequence
- End of the First PCR Cycle
On a crime scene, the specimen that can be used for PCR testing are blood and body secretions.
PCR testing can be done on a scene with blood spills.
Learn more about gel electrophoresis here:
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Answer:
The correct option is <em>3. they break down rock into soil in which plants can grow</em>
Explanation:
When a disaster is such huge that even the soil and organic matter get removed from the place, then the succession that will occur in such kind of place will be termed as primary succession. For example, a volcanic eruption or an earthquake.
On the other hand, if after a disaster some of the organic matter remains on the land, then the succession that will occur will be termed as secondary succession. E.g a succession after fire
In primary succession, the pioneer species will be plants that require less soil such as the lichens. The lichens will break down the rocks into the soil and eventually new species of plants will start to grow on the land.
Answer:
A mature animal will have been fully developed whereas an immature animal will not be fully developed. In a mature animal, all stages of development will have occurred whereas in an immature animal not all developmental stages would have occurred.
A mature animal will be better adapted to live in an environment as compared to an immature animal.
