<h2>Development of Plant Needles</h2>
Explanation:
- Seed of pitch pine treated with colchicine delivered tetraploid seedlings which had thick and sporadic needles and less fortunate tallness and diameter growth than ordinary seedlings.
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In test of colchicine-initiated polyploidy in pines, researcher found that a significant number of the polyploid plants returned to a diploid development in light of the fact that the polyploid cells partitioned at a more slow rate and were overwhelmed by the more quickly developing diploid cells which encompassed them.
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The primary needles of both diploid and polyploid plants were more effective at low light intensity than secondary needles, and they had lower compensation points.
A mutation that involves one or a few nucleotides is called
a) mutagen
b) inversion
c) point mutation
d) translocation
Answer:
c) point mutation
Explanation:
When only one or a few nucleotides of a gene are changed by mutation, this is called a point mutation. A point mutation can add one additional nucleotide to the wild type gene or may delete or substitute a nucleotide from it. For example, if a wild type gene sequence is "ATATATATA", then the addition of "C" at the position 4 will change it into "ATACTATATA". This addition of new nucleotide is called point mutation since only one nucleotide is added to the gene. Point mutations can cause serious genetic disorders such as sickle cell anemia.
The medulla oblongata is a primary respiratory control center. It’s main function is to send signals to the muscle that controls respiration to cause breathing to occur. There are two regions in the medulla that control respiration the ventral respiratory group stimulates expiratory movement.
Answer:
Weathering describes the breaking down or dissolving of rocks and minerals on the surface of the Earth. Water, ice, acids, salts, plants, animals, and changes in temperature are all agents of weathering.
Once a rock has been broken down, a process called erosion transports the bits of rock and mineral away. No rock on Earth is hard enough to resist the forces of weathering and erosion. Together, these processes carved landmarks such as the Grand Canyon, in the U.S. state of Arizona. This massive canyon is 446 kilometers (277 miles) long, as much as 29 kilometers (18 miles) wide, and 1,600 meters (1 mile) deep.
Weathering and erosion constantly change the rocky landscape of Earth.
Explanation:
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