Transport proteins (carrier proteins and channel proteins) allow substances into and out of the cell that cannot pass through the phospholipid bilayer (as they’re either to large, charged or not lipid soluble) by facilitated diffusion.
Specifically channel proteins allow ions into and out of the cell by creating a pore in the membrane in which they can move through with their concentration gradient
Answer:
A. Constipation
Explanation:
As there would be easy passage of faeces, based on an increase in roughage for the colon to press and rub against
Answer:
peptide antigens by MHC class II molecules
Explanation:
Helper T cells are activated by peptide antigens by MHC class II molecules. These antigens express on the surface of antigen-presenting cells (APCs). After activation, the T helper cells divide and secrete cytokines to assist the immune response.
Answer: Homologous chromosomes are the pairs of chromosomes that having same gene sequence, equal length of arms and centromere location. Homologous chromosomes have two homolog one come from male parent and other come from female parent.
Explanation:
These chromosomes Are formed for the purpose of genetic variations. They are called homologous because when two same structured exist it form pair together
Answer: The greenhouse gas emissions from the extraction of bitumen and the use of large quantities of water.
Explanation:
Bitumen is a natural flammable organic matter formed from kerogen in the process of petroleum generation, which is soluble in carbon disulfide. Asphalt and mineral wax are examples of hydrocarbons which are part of bitumen. Conventional oil is extracted by wells while <u>oil sands deposits are extracted using surface mining sectioning techniques, or are flowed to wells by in situ techniques that reduce bitumen viscosity by steam and/or solvents.</u> So, unlike crude oil extracted in oil wells, bitumen requires an open-pit mining operation, in which large tracts are washed with a mixture of water and chemicals to separate the bitumen from a mixture of sand and clay.
Two consequences of this practice are:
- The greenhouse gas emissions from the extraction of bitumen are larger than the extraction of conventional oil. The emissions produced contribute to enhance the greenhouse effect and cause global warming. The greenhouse effect occurs when certain gases retain part of the energy emitted by the earth's soil when heated by the sun's radiation. This phenomenon occurs naturally, and thanks to it, the average temperature of the Earth is about 14º C (57.2 °F). The problem occurs when these greenhouse gases increase in the atmosphere and the amount of energy that is not released into space also increases and, with it, the Earth's temperature.
- The extraction of bitumen from oil sands requires the use of large quantities of water, and even though water used here can be recycled, only a small amounts is returned to the natural cycle. Also, spills from the transportation of the oil could damage soils and waterways, increasing water pollution. This toxic water could get into surface.
