Question

what molecule is involved in active transport?
why can’t water “directly” pass through a phosolopid bilayer?

1. the dots below represents a solute (e.g sugar) in the solvent water, separated by a semipermeable membrane. which direction will osmosis occur? label each side as isotonic, hypertonic, or hypotonic in the diagram.

unit 1: instructional sequence 5:
sc.912.l.18.7 identify the reactants, products, and basic functions of photosynthesis. students should know that light is measured by intensity and both temperature and light intensity can affect some plants growth and be able to interpret graphs measuring both compared to growth.

1. the rate at which photosynthesis occurs is not always the same. the intensity of light, temperature, supply of carbon dioxide, supply of water, and availability of minerals are important factors that affect the rate of photosynthesis in land plants. the rate also varies by species and a plant’s health and maturity. the two graphs below show the effects of light intensity and temperature on the rate of photosynthesis in land plants. these two factors affect many enzymes that control photosynthetic reactions. use the graphs below and answer questions

what type of biomolecule is an enzyme?
explain what the graph on the left tells about the effect of light intensity on the rate of photosynthesis.
explain what the graph on the right tells about the effect of temperature on the rate of photosynthesis.
what happens to the rate of photosynthesis when the temperature rises above 33°c?

Explanation:

1. What molecule is involved in active transport?

• ATP (Adenosine - Tri - Phosphate) provides the energy for active transport. It is hydrolyzed to release energy that is used to move substances against their concentration gradient.

1. Why can't water “directly” pass through a phospholipid bilayer?

• The interior of the phospholipid bilayer is hydrophobic. Water is a polar molecule, and polar molecules have difficulty passing through the non - polar hydrophobic region of the bilayer.

1. For the osmosis question:

• Osmosis is the movement of water from an area of low solute concentration (hypotonic) to an area of high solute concentration (hypertonic). Without seeing the actual dot distribution, in general, water will move towards the side with more solute particles. The side with fewer solute particles is hypotonic and the side with more solute particles is hypertonic. If the solute concentrations are equal, the sides are isotonic.

1. What type of biomolecule is an enzyme?

• Most enzymes are proteins. However, some RNA molecules can also act as enzymes (ribozymes). But in general, enzymes are considered proteins.

1. Effect of light intensity on the rate of photosynthesis (left graph):

• As light intensity increases from 0, the rate of photosynthesis increases. However, at a certain point (saturation point), further increases in light intensity do not lead to an increase in the rate of photosynthesis. This is because other factors such as the availability of carbon dioxide, water, or the number of photosynthetic pigments become limiting.

1. Effect of temperature on the rate of photosynthesis (right graph):

• As temperature increases from 0, the rate of photosynthesis increases up to an optimal temperature (around 25 - 30°C in this graph). This is because enzymes involved in photosynthesis work more efficiently at higher temperatures within a certain range. Beyond the optimal temperature, the rate of photosynthesis decreases because the enzymes start to denature.

1. What happens to the rate of photosynthesis when the temperature rises above 33°C?

• The rate of photosynthesis decreases as the temperature rises above 33°C because the enzymes involved in photosynthetic reactions start to denature at higher temperatures, reducing their efficiency.

Answer:

1. ATP
2. Water is polar and the interior of the phospholipid bilayer is hydrophobic.
3. Water moves towards the hypertonic side; identify sides as hypotonic, hypertonic, or isotonic based on solute concentration.
4. Protein (mostly)
5. Rate increases with light intensity until saturation point.
6. Rate increases to an optimal temperature then decreases.
7. The rate decreases.