Answer:
The mechanisms of transport across the cell membrane are as follow: 1- simple diffusion, 2- facilitated diffusion, 3- primary active transport and 4-secondary active transport
Explanation:
The cell membrane is a selectively permeable structure capable of transporting substances by different mechanisms. Simple diffusion is a type of passive transport (i.e. does not require energy) where non-polar molecules (e.g. O2, CO2) pass across the membrane by a process that does not require energy from the cell. Facilitated diffusion is another type of passive transport where larger polar molecules (e.g., glucose and amino acids) pass across the membrane by using specific transmembrane integral proteins. On the other hand, primary active transport is a type of active transport that uses chemical energy (e.g., ATP) to move substances such as metal ions (Na+, K+, Ca2+) across the cell membrane against their concentration gradient. Finally, secondary active transport is another type of active transport where transporter proteins are used to couple the movement of ions (e.g., H+ protons) down their electrochemical gradient to the transport of another ions/solutes against their concentration/ electrochemical gradient.
accumulations of genetic mutations over time.
Genetic and epigenetic changes compound over time to cause cancer. While aging and chronic inflammation are the major causes of epigenetic changes, carcinogenic substances, UV radiation, and other conditions can also cause genetic changes. Our prior exposure levels and life history are reflected in the accumulation and patterns of changes in normal cells. The majority of accumulated changes are regarded as passengers, although they are linked to cancer drivers as they accumulate. Although only hypothesized for genetic changes, this has been demonstrated for aberrant DNA methylation. However, modern technology has made it possible to assess uncommon point mutations, and research has revealed that the rates of their accumulation do actually correspond with cancer risk.
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Answer:
d. They are often keystone species
Explanation:
Top predators in an environment are the largest predators and sits on the top (apex) of the food chain in an ecosystem which do not have any natural predators.
As the top predators relative to its abundance has disproportionately large effect on its natural environment, they are the keystone species most of the time.
Hence option d. They are often keystone species is the right option.
Answer:Nucleotids
Explanation:
Many plants have waxy coatings on some surfaces. This coating reduces water loss because it is not water-permeable. This waxy coating is which type of organic molecule? a biomolecule that is a large, complex set of chains composed of alternating subunits called nucleotids has what function in the cell?
