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 are the different ways in which glucose is oxidised to provide energy in various organisms?
What criteria do we use to decide whether something is alive?
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 the components of the transport system in highly organised plants?
What are outside raw materials used for by an organism?
What would be the consequences of a deficiency of haemoglobin in our bodies?
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?
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.
(a) What property do all elements in the same column of the Periodic Table as boron have in common?
(b) What property do all elements in the same column of the Periodic Table as fluorine have in common?
How is the sex of the child determined in human beings?
State the principle of an electric generator.
State Fleming’s left-hand rule.
State the rule to determine the direction of a (i) magnetic field produced around a straight conductor-carrying current, (ii) force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it, and (iii) current induced in a coil due to its rotation in a magnetic field.
A milkman adds a very small amount of baking soda to fresh milk.
(a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd?
At the time of short circuit, the current in the circuit
(a) reduces substantially.
(b) does not change.
(c) increases heavily.
(d) vary continuously.
What is a good source of energy?
Why don’t two magnetic field lines intersect each other?