One of them is the variance of the gene pool--in other words, the genetic adaptations plants and animals have help them to survive. That is where the phrase "survival of the fittest" comes from; if one is not genetically fit to survive in their environment, they will die off and their genes will not be added to the gene pool, making it easier for organisms with more fit genes to reproduce and add to the gene pool.
Another is the availability of resources. It is very hard for an organism to survive without food, water, and shelter. If the organisms of a species live in an environment with a lack of resources, they will die off, thus making them unable to reproduce and therefore go extinct.
Also, the presence of predators makes it difficult for a species to survive. Predators preying on prey make prey poulations go down and predator populations go up. However, going back to the gene pool, many organisms have adapted to hiding from predators with means such as camouflage or burrowing.
Finally, the general conditions of their environment. This one is self-explanatory. For example, you would not expect to find a polar bear in the desert or a cactus in the Arctic. The conditions are simply not right for their survival and they will die off. This is also why birds migrate--they need to go somewhere warm in the winter to keep themselves warm!
The veinlets form a network in the leaf lamina that is why the type of venation reticulate meaning network. So all dicots have dicotyledonous seeds, a tap root system and leaves with reticulate venation. ( with some exceptions of dicots having parallel venation in leaves like Calophyllum)
In fixation, the first stage of the Calvin cycle, light-independent reactions are initiated; CO2 is fixed from an inorganic to an organic molecule. In the second stage, ATP and NADPH are used to reduce 3-PGA into G3P; then ATP and NADPH are converted to ADP and NADP +, respectively.
1. Latitude or distance from the equator – Temperatures drop the further an area is from the equator due to the curvature of the earth. In areas closer to the poles, sunlight has a larger area of atmosphere to pass through and the sun is at a lower angle in the sky.
2. Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context (e.g., aviation, geometry, geographical survey, sport, or atmospheric pressure). Although the term altitude is commonly used to mean the height above sea level of a location, in geography the term elevation is often preferred for this usage.
3. Large bodies of water, such as oceans, seas and large lakes, can affect the climate of an area. Water heats and cools more slowly than landmasses. Therefore, the coastal regions will stay cooler in summer and warmer in winter, thus creating a more moderate climate with a narrower temperature range.
4. Ocean currents can be caused by wind, density differences in water masses caused by temperature and salinity variations, gravity, and events such as earthquakes or storms. Currents are cohesive streams of seawater that circulate through the ocean