Biology Times (^19)
March
(c) Photolysis of water
(d) chlorophyll synthesis
- Nitrogen -fixation in root nodules of Alnus is
brought about by (AIPMT 2009,2008)
(a) Bradyrhizobium (b) Clostridium
(c) Frankia (d) Azorhizobium - Which of the following is a flowering plant with
nodules containing filamentous nitrogen - fixing
microorganism? (AIPMT 2007)
(a) Casuarina equisetifolia
(b) Crotalaria juncea
(c) Cycas revoluta
(d) Cicer arietinum - Which one of the following element is not an
essential micronutrient for plant growth?
(AIPMT 2007)
(a) Mn (b) Zn
(c) Cu (d) Ca - The translocation of organic solutes in sieve tube
members is supported by (AIPMT 2006)
(a) P-Proteins
(b) Mass flow involving a carrier and ATP
(c) Cytoplasmic streaming
(d) Root pressure and transpiration pull - The major role of minor elements inside living
organisms is to act as (AIPMT 2003)
(a) Binder of cell structure
(b) Cofactor of enzymes
(c) Building blocks of important amino acids
(d) Constituent of hormones - Grey spots of oat are caused by deficiency of
(AIPMT 2003)
(a) Fe (b) Cu
(c) Zn (d) Mn - Which aquatic fern performs nitrogen fixation?
(AIPMT 2001)
(a) Azolla (b) Nostoc
(c) Salvia (d) Salvinia
1.(c)
2.(a) The essential elements which are used in
relatively large amounts by plants for their
growth are called macronutrients. Carbon,
oxygen, hydrogen, nitrogen, sulphur, phosphorus,
potassium, magnesium and calcium are
macronutrients. The essential elements which
are required in minute quantities by plants for plant
growth are called micronutrients. Iron, boron,
manganese, zinc, copper, molybdenum, chlorine
and nickel are micronutrients.
In the given choices, none of the options
represents three macronutrients as asked in the
question. All the options are a combination
of macro and micronutrients
3.(b) Leg-haemoglobin acts as a oxygen scavenger
and it helps in prevention of oxygen by which
nitrogenase will be active
4.(b) Minerals which are required by the plants in
larger quantities are called macronutrients, while
the minerals which are required by the plants in
very small amounts are called micronutrients.
Carbon, hydrogen, oxygen, nitrogen, sulphur,
phosphorus, calcium, potassium and magnesium
are macronutrients.- (a) The deficiency symptoms of nitrogen is
chlorosis and potassium is yellow edges of
leaves and scorching of older leaves. Deficiency
symptoms are first visible in the older leaves.
6.(d) Some plants have symbiotic relationship,
similarly Glomus is a genus of arbuscular
mycorrhizal fungi , which is helpful in uptake of
potassium from the soil.
7.(a) Nitrogenase enzyme required for nitrogen
fixation requires anaerobic condition,
leghaemoglobin is an oxygen scavenger which is
helpful in removal of oxygen. - (d) Nitrifying bacteria oxidise ammonia to nitrates
which is chemosynthetic bacteria, the conversion
occurs in two steps, first step a m m o n i a
is oxidised to nitrite by nitrosomonas/nitrococcus.
In the second step, nitrite is oxidised to nitrate by
nitrobacter/ nitrocystis. - (a) Calcium element is a part of structural
component of the cell and are not released.in case
of elements which are not remobilised the
deficiency symptoms first appear in the young
leaves. - (b) Magnesium is a macronutrient 0.2 - 4% dry
matter which is necessary for normal plant growth.
Mg has an important role in photosynthesis
because it forms the central atom of chlorophyll. - (b) Azospirillum is a nitrogen bacteria in paddy
fields. It is a symbiotic N 2 fixing bacteria. When
bacterium is added to the soil it increases nitrogen
supply 20-40 kg per hectare per season. - (c) The main function of manganese is splitting of
water to liberate oxygen during photosynthesis.
In plants Mn is absorbed as manganous ions