SB6 Flashcards
Explain why photosynthetic organisms are producers of biomass.
They convert energy from the sun into glucose during photosynthesis producing biomass.
Recall some substances produced from glucose and their roles in the plant.
Cellulose- building cell walls
Starch- stored in seeds and plant parts as a food source
Summarise what happens in photosynthesis (including the use of a word equation).
During photosynthesis: light energy is absorbed by chlorophyll - a green substance found in chloroplasts in the palisade cells in the leaf. absorbed light energy is used to convert carbon dioxide (from the air) and water (from the soil) into a sugar called glucose. oxygen is released as a by-product.
Carbon dioxide + water + (light energy) → glucose + oxygen gas
Explain why photosynthesis is an endothermic reaction.
Photosynthesis requires energy to drive the chemical reaction. Photosynthesis is an endothermic reaction. This means it cannot occur without energy (from the Sun).
Explain how a leaf and its cells are adapted for photosynthesis.
By having a large surface area, and contain openings, called stomata to allow carbon dioxide into the leaf and oxygen out.
Recall what is meant by a rate of reaction.
The rate of a reaction is a measure of how quickly a reactant is used up, or a product is formed.
Describe the effects of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis.
Increase in CO2 concentration and light intensity increases photosynthesis. Increasing temperature also does this as more collisions occur although it can become too much in extremes.
Explain why the rate of photosynthesis is
inversely proportional to the distance of a light
source.
This is because as the distance away from a light source increases, photons of light become spread over a wider area.
Explain how root hair cells are adapted to
taking in water and mineral ions.
- Having large surface area to increase rate of absorption
- They also have lots of mitochondria to release energy from glucose during respiration in order to provide the energy needed for active transport
Recall that substances can be transported by
diffusion, osmosis and active transport.
Diffusion- Carbon dioxide, oxygen, water, food substances, wastes, eg urea
Osmosis- Water
Active transport- Mineral ions into plant roots. Glucose from the gut into intestinal cells, from where it moves into the blood
What is active transport
Substances more from low to higher concentration up a concentration gradient
Explain how xylem tissue is adapted to its
functions.
- They lose their end walls so the xylem forms a continuous, hollow tube.
- They become strengthened by a substance called lignin. Lignin gives strength and support to the plant.
Explain how phloem tissue is adapted to its
functions.
- growing parts of the plant for immediate use
- storage organs such as bulbs and tubers
- developing seeds
Describe now transpiration occurs.
Transpiration is the process in which plants release the water inside it in the form of moisture or water vapor. Roots consume some amount of water from the soil and the rest evaporates in the atmosphere. Parts of plants such as stems, small pores on leaves, and flowers evaporate the water to the atmosphere.
Describe how translocation occurs.
Translocation is the movement of sugar produced in photosynthesis to all other parts of the plant for respiration and the other processes described above. This occurs in phloem cells.
