List of practice Questions

Rudolf Virchow modified the hypothesis of cell theory given by Schleiden and Schwann Cell theory says that all cells arise from pre existing cells

Primary growth of the plants contributes to the elongation of the plants along their axis. Root apical meristem and shoot apical meristem are responsible for primary growth of the plants.

Purine bases present in $DNA$ are adenine and guanine. The base thymine is present in $RNA$ while base uracil is present in $DNA$.

$pK_a$ value of phenol is $10.0$ while that of ethanol is $15.9$ Ethanol is stronger acid than phenol.

Phloem fibres or bast fibres are made up of collenchymatous cells. Phloem fibres are generally found in primary pholem.

Photorespiration is a wasteful process. In photorespiratory pathway, there is no synthesis of sugars or$ ATP$.

$ PHBV$ is a biodegradable polymer. $ PHBV$ is an aliphatic polyester.

Phenotypic superiority of hybrid over either of its parents in one or more traits is termed hybrid vigour. Suppression of expression of recessive harmful genes occurs in heterozygotes.

Pascal?? law is the working principle of hydraulic lift Pressure $= \frac{thrust}{arer}$

Periodic abstinence is a method in which couples avoid from coitus from day $17$ to $27$ of menstrual cycle. Periodic abstinence is a very effective method and $100 \%$ sure of birth control.

Pancreas is a heterocrine gland Endocrine part secretes insulin and glucagon and exocrine part secretes an acidic pancreatic juice containing enzymes

Pairing and separation of pair of chromosomes would lead to segregation of a pair of factors they carried. Two alleles of a gene pair are located on similar sites on non-homologous chromosomes.

Oxidation state of oxygen in $OF_{2}$ and $Na_{2}O$ is $+2$ and $-2$ respectively. Oxygen is an electronegative element.

Oxytocin is called 'milk-ejection hormone'. Oxytocin acts on the smooth muscles of uterus and stimulates its contraction.

Osmosis is a special type of diffusion of water through a semi-permeable membrane. The net direction and rate of osmosis depends only on the pressure gradient.

Over-exploitation of a species reduces the size of its population eventually leading to its extinction. Steller's sea cow is a large, herbivorous, terrestrial mammal which is on the verge of extinction due to over exploitation.

$O_{2}$ molecule is diamagnetic while $C_{2}$ molecule is paramagnetic in nature. Bond order of $O_ 2$ molecule is $1.5$ and that of $C_2$ molecule is $2.5$.

Neurons protect and support the neuroglial cells Neuroglial cells make up ninety per cent neural tissue in our body

$Na_{2}O$ is basic oxide whereas $Cl_{2}O_{7}$ is acidic oxide. Elements on extreme left form basic oxides whereas elements on extreme right form acidic oxides.

Nephrons are of two types : cortical and juxtamedullary according to their relative position in the cortex Juxtamedullary nephrons have short loop of Henle while cortical nephrons have long loop of Henle

Myelinated nerve fibres are present in spinal and cranial nerves Myelinated nerves conduct impulses more rapidly than unmyelinated nerves

n: The stage between the two meiotic divisions is called interkinesis. : Interkinesis is generally short lived.

Moon has no atmosphere. The escape velocity for moon is less than that for earth.

Mycoplasmas are pathogenic in animals and plants. Mycopiasmas lack cell wall and can survive without oxygen.

Monoadelphous stamens are found in pea. In pea, stamens are united into one bunch or one bundle.