Multiple Choice QuestionsThe function of leghaemoglobin during biological nitrogen fixation in root nodules of legumes is to
convert atmospheric N2 to NH3
convert ammonia to nitrite
transport oxygen for activity of nitrogenase
protect nitrogenase from oxygen
D.
protect nitrogenase from oxygen
Rhizobium is the nitrogen fixing bacteria present in root nodules of leguminous plants. Roots of a legume secrete chemical attractants flavonoids and betaines. Bacteria collect over the root hairs, release nod factors that causes curling of root hairs around the bacteria, degradations of cell wall and formation of an infection thread enclosing bacteria. The infected cortical cells differentiate and start dividing. It produces swelling of nodules and the infected cells enlarge. Bacteria stop dividing and form irregular polyhedral structures called bacteroids. The host cells develops a pinkish coloured pigment called leghaemoglobin. It is an oxygen scavenger and protects nitrogenase from oxygen. Symbiotic nitrogen fixation requires co-operations of 'Nod' genes of legumes, 'nod' 'nif' and 'fix' genes of bacteria.
Leghaemoglobin helps in
imparting colour to floral petals
protecting nitrogenase from O2
destroying bacteria
transport of food in plants
B.
protecting nitrogenase from O2
Leghaemoglobin is a pinkish pigment present inside the root nodules of nitrogen fixing plants like legumes. It is an oxygen scavenger and is related to blood pigment haemoglobin. It protects nitrogen fixing enzyme nitrogenase from oxygen. The most important bacteria present inside the nodules is Rhizobium.
Which among the following is a rootless plant?
Nymphaea
Sagittaria
Ceratophyllum
Vallisneria
C.
Ceratophyllum
All the given options are hydrophytes in nature which grow in extremely wet or watery conditions. But among them only in Ceratophyllum roots are completely absent even in embryonic stage. They remain under water completely Nymphaea is a rooted hydrophyte with floating leaves.
Vallisneria is rooted submerged hydrophyte and Sagittaria is rooted emergent hydrophyte.
Hydroponics is
nutrient less culture
water less culture
soilless culture
none of these
C.
soilless culture
Hydroponics is a subset of hydroculture, which is a method of growing plants without soil by using mineral nutrient solutions in a water solvent. It is useful in areas having thin, infertile and dry soils. They conserve water. It can regulate pH optimum for a particular crop, control soil borne pathogens, avoid problems of weeding and obtain consistently better yield.
The enzyme responsible for atmospheric nitrogen fixation is
nitrogenase
hydrogenase
oxygenase
carboxylase
A.
nitrogenase
Enzyme nitrogenase plays a key role in N, fixations and remains active only during anaerobic condition. It is made up of two protein subunits :
i) non-heme iron protein or Fe-protein or dinitrogen reductase.
ii) Iron molybdenum protein or Mo-Fe protein or dinitrogenase
Insects captured by insectivorous plants fulfil their requirements of
enzymes
oxygen
nitrogen
water
C.
nitrogen
The insectivorous plants grow in nitrogen deficient soil and their nitrogen requirement is fulfilled by capturing and digesting the insects.
Examination of blood of a person suspected of having anaemia, shows large, immature, nucleated erythrocytes without haemoglobin. Supplementing his diet with which of the following is likely to alleviate his symptoms?
Thiamine
Folic acid and cobalamine
Riboflavin
Riboflavin
D.
Riboflavin
Anaemia refers to any condition in which there is an abnormally low haemoglobin concentration and/or blood cell count. The most common cause is deficiency of iron which is an essential element of haemoglobin molecule.
Thus, the iron compounds in the diet will help to alleviate the symptoms of anaemia.
Thiamine (vitamin B1), deficiency causes beri-beri.
Riboflavin (vitamin B2) deficiency causes cheilosis and skin diseases.
The deficiencies of micro-nutrients, not only affects growth of plants but also vital functions such as photosynthetic and mitochondrial electron flow. Among the list given below, which group of three elements shall affect most, both photosynthetic and mitochondrial electron transport ?
Cu, Mn, Fe
Co, Ni, Mo
Mn, Co, Ca
Ca, K, Na
A.
Cu, Mn, Fe
Micronutrients are minerals obtained from the soil and present in plant tissues at concentrations usually less than 3 mol g-1 dry matter. Copper (Cu), Manganese (Mn) and Iron (Fe) are the micronutrients which affect both photosynthesis and mitochondrial electron transport as they are the main constituents of various electron carriers.
Which one of the following elements is not an essential micronutrient for plant growth?
Mn
Zn
Cu
Cu
D.
Cu
Ca is essential macronutrient for plant growth. It is constituent of middle lamella, activator of enzymes, connected with chromosome formation and many aspects of metabolism
Which of the following is correct set of micronutrient for plants?
Mg, Si, Fe, Cu, Ca
Cu, Fe, Zn, B, Mn
Mg, Fe, Zn, B, Mn
Mo, Zn, Cl, Mg, Ca
B.
Cu, Fe, Zn, B, Mn
Plants require nutrients for proper growth and development. There are 16 elements which are required for plant and are termed as essential elements. They are as follows:
Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Sulphur (S), Potassium (K), Magnesium (Mg), Calcium (Ca), Iron (Fe), Copper (Cu), Boron (B), Zinc (Zn), Manganese (Mn), Molybdenum (Mo) and Chlorine (Cl).
The essential elements are categorised into 2 groups,
