How is food transported in plants?
Food transportation occurs by the phloem in the plants. Transportation of food is a downward movement and is the active process. Phloem is composed of mainly four components- sieve tube elements mainly for sugar transport, companion cells carry all metabolic functions of sieve tubes, phloem fibres provide tension strength and phloem parenchyma cells helps in transfer of food also called transfer cells. Transportation of food in the form of organic solutes from one place to another place in the higher plants are known as translocation process. In this, carbohydrates are translocated from leaves to the roots and then in the storage organs like tubers, bulbs, fruits etc. along to the phloem in the form of sugar (sucrose). They are transported through the sieve elements of the phloem and this translocation needs the metabolic energy to transport the food. They use this metabolic energy in the form of ATP food in the form of organic solutes loaded into the sieve elements of the phloem vascular tissue and by the process of osmosis water enters in the sieve tubes that raise the pressure in the phloem and then the food is transported to the parts of the plants. Transportation of food movement involves along the turgor pressure gradient that is induced by maintained gradient of water potential; and the flow of organic solutes takes place from the high concentration to the lower concentration, i.e, from leaves to the roots and the organs.
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
How is the amount of urine produced regulated?
What criteria do we use to decide whether something is alive?
What are the different ways in which glucose is oxidised to provide energy in various organisms?
The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
(a) cytoplasm. (c) chloroplast.
(b) mitochondria. (d) nucleus.
What are the differences between autotrophic nutrition and heterotrophic nutrition?
What are outside raw materials used for by an organism?
What would be the consequences of a deficiency of haemoglobin in our bodies?
What are the components of the transport system in highly organised plants?
What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
What is a good source of energy?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the difference between a reflex action and walking?
What is the importance of DNA copying in reproduction?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
On what factors does the resistance of a conductor depend?
How can three resistors of resistances 2 Ω, 3 Ω, and 6 Ω be connected to give a total resistance of (a) 4 Ω, (b) 1 Ω?
Compare and contrast bio-mass and hydro electricity as sources of energy.
Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H2SO4.
State Fleming’s left-hand rule.
Why do you think that there should be equitable distribution of resources? What forces would be working against an equitable distribution of our resources?
Identify the substances that are oxidised and the substance that are reduced in the following reactions.
(i) 4Na(s) + O2(g) → 2Na2O(s)
(ii) CuO(s) + H2(g) → Cu(s) + H2O(l)
Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?
Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V.
What is ozone and how does it affect any ecosystem?