Covalent bonds is important in four macromolecules such as proteins (polymers of amino
acids), nucleic acids (polymers of nucleotides), carbohydrates (polymers of
sugars) and lipids (with a variety of modular constituents) because they served
as a basic structure of macromolecules.
In addition, the resulting covalent bond is a result
of sharing a pair of electrons, one from each atom or molecular units.
Answer:
1. High osmotic pressure due to the hypersaline nature of marine habitats
2. The dependence of flowering plants on pollinating insects for fertilization. These insect pollinators are however, absent in the marine environment.
3. Competition from already-established sea weeds and grasses provides another challenge to flowering plants invadingnthe oceans.
4. Constant changes in the environment as well as temperature changes too
Explanation:
The marine environment is a hypersaline environment with a high salt concentration relative to that of the plant cell. Due to high salt concentration of the marine environment, their is high osmotic pressure on living oragnisms found therein. Organisms must have well-adapted osmo-regulatory mechanisms to counteract the high osmotic pressure of their environment. Therefore, flowering plants face the challenge of removing excess salt from their cells or else lose water to their environment, hence resulting in the death of the plant. However, most flowering plants lack this ability and thus, have found it difficult to invade the oceans.
Flowering plants depends on insect-pollinators for fertilization. However, these insect are not found in the oceans, and as such, it is difficult for flowering plants to invade the oceans.
Well-adapted seaweeds and grasses serve as competitors for any invading flowering plant. Since the flowering plants are not yet adapted for life in marine habitats, they lose out in this competition.
The oceans are constantly in a state of frequent turbulence and change due to tides and currents. Also, the temperature of the oceans are very low and fluctuations in the temperatures of the ocean do occur, utimately serving as obstacles to invading flowering plants to adapt to life in the oceans and seas.
The compound eye and eye is built differently from the vertebrate eye
4.3 Agricultural land. At present some 11 percent (1.5 billion ha) of the globe's land surface (13.4 billion ha) is used in crop production (arable land and land under permanent crops). This area represents slightly over a third (36 percent) of the land estimated to be to some degree suitable for crop production.
Answer:
However, extreme high temperatures can cause an enzyme to lose its shape (denature) and stop working. pH: Each enzyme has an optimum pH range. Changing the pH outside of this range will slow enzyme activity. Extreme pH values can cause enzymes to denature.
Explanation:
