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 outside raw materials used for by an organism?
What are the components of the transport system in highly organised plants?
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?
Name
(a) three elements that have a single electron in their outermost shells.
(b) two elements that have two electrons in their outermost shells.
(c) three elements with filled outermost shells.
How does our body respond when adrenaline is secreted into the blood?
10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HCl. If we take 20 mL of the same solution of NaOH, the amount HCl solution (the same solution as before) required to neutralise it will be
(a) 4 mL (b) 8 mL (c) 12 mL (d) 16 mL
Asexual reproduction takes place through budding in
(a) amoeba.
(b) yeast.
(c) plasmodium.
(d) leishmania.
Name the substance which on treatment with chlorine yields bleaching powder.
A copper wire has diameter 0.5 mm and resistivity of 1.6 × 10–8 Ω m. What will be the length of this wire to make its resistance 10 Ω? How much does the resistance change if the diameter is doubled?
How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?
How does chemical coordination occur in plants?
Why is a normal eye not able to see clearly the objects placed closer than 25 cm?
On what factors does the resistance of a conductor depend?