NEET Practice Questions (MCQs) with Answers & Solutions

The NCERT text states: 'Oxygen helps in releasing metabolic energy essential for growth activities.' (Chapter: PLANT_GROWTH_AND_DEVELOPMENT, Section 13.1.5).

The NCERT text says: 'Nutrients (macro and micro essential elements) are required by plants for the synthesis of protoplasm and act as source of energy.' (Chapter: PLANT_GROWTH_AND_DEVELOPMENT, Section 13.1.5).

The NCERT text explains: 'This ability of the plants is due to the presence of meristems at certain locations in their body. The cells of such meristems have the capacity to divide and self-perpetuate. The product, however, soon loses the capacity to divide and such cells make up the plant body. This form of growth wherein new cells are always being added to the plant body by the activity of the meristem is called the open form of growth.' (Chapter: PLANT_GROWTH_AND_DEVELOPMENT, Section 13.1.1).

Relative growth rate is calculated per unit initial parameter. If both leaves increase by the same absolute amount (5 cm²), the leaf with a smaller initial area will have a higher relative growth rate (percentage increase) compared to a larger leaf. For example, if Leaf A is 10 cm² and grows to 15 cm², its relative growth is 50%. If Leaf B is 100 cm² and grows to 105 cm², its relative growth is 5%. (Chapter: PLANT_GROWTH_AND_DEVELOPMENT, Section 13.1.4 and Figure 13.7).

According to the NCERT text, 'The centre of mass moves as if all the mass of the system is concentrated at this point and all the external forces act at it.' This is a fundamental concept in the motion of the center of mass.

The NCERT text states: 'By using symmetry consideration, we can easily show that the centres of mass of these bodies [homogeneous bodies of regular shapes like rings, discs, spheres, rods etc.] lie at their geometric centres.' For a thin rod, its geometric center is its midpoint.

The NCERT summary clearly defines the position vector of the centre of mass of a system of n particles as $R = \frac{1}{M} \sum m_i r_i$, where $M$ is the total mass of the system.

The NCERT text states: 'If we choose, the centre of mass as the origin of our coordinate system, $R = 0$, i.e., $\int r dm = 0$.' This implies that the weighted average position of all mass elements relative to the center of mass is zero.

The NCERT text provides the coordinates of the center of mass for a continuous mass distribution as $X = \frac{1}{M} \int x dm$, $Y = \frac{1}{M} \int y dm$, $Z = \frac{1}{M} \int z dm$. Since $M = \int dm$, options (2) and (3) are equivalent and both correctly represent the coordinates.

The summary states: 'In pure translation, every particle of the body moves with the same velocity at any instant of time.' This is a defining characteristic of pure translation.