Answer:
The cell membrane is semi-permeable. It allows some molecules to enter easily inside the cell whereas some molecules are blocked from entering the cell.
Small, polar molecules and hydrophobic molecules enter easily through the cell membrane. But large molecules and ions cannot easily move inside the cell membrane.
A hydrophilic substance like the substance L mentioned in the question enters the cell membrane through the help of carrier proteins. The substance attached to the large protein might enter through active or passive diffusion but it can only enter the cell by attaching to carrier proteins.
Answer:
Dust bowl resulted from extreme drying and loosening of the soil that resulted in soil erosion by wind. Thus, it can be related that poor agricultural practices like over plowing , over grazing and leaving the land barren are human activities that must have contributed to the dust bowl.
Explanation:
- Dust bowl is referred to a period in early twentieth century when the the American and Canadian prairies faced severe dust storms.
- These dust storms resulted from severe drought and failure of practices to prevent soil erosion.
- Several people and livestock died as a result of choking.
- Over plowing, removal of top soil and small grasses exposed the soil to eroding winds and caused the dust storms.
Answer and explanation;
-All lipids contain carbon, hydrogen, and oxygen. Some of them also contain nitrogen and phosphorus. The four main classes of lipids are fats, waxes, sterols, and phospholipids. Fats are triglycerides.
-The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes.
-Lipids are water-insoluble (hydrophobic), and this property is put to great use in the organisation of cells and tissues.
For example; phospholipids are a class of lipids that is amphipathic; that is it contains fatty acid tails that are hydrophobic, and a phosphate head that is hydrophilic. This means the phosphate group will orientate itself towards water and away from the rest of the molecule, and also gives rise to the special properties that allow phospholipids to be used to form membranes.
Answer:
Basal meristems
Explanation:
Meristems are the portion of plants able to generate any kind of new tissues. Therefore, the way plants keep their meristems protected is related to climate adaptation.
Grasslands tend to be arid ecosystems, so grasses have developed basal meristems, meaning they spend the dry season very close or under soil, where water evaporates slowlier than above surface, until wet season allows meristems to generate new stems and leaves.
This disposition is also useful in cases of fire and grazing, which are also frecuent in grasslands.
