In human beings, the statistical probabi | Class 10 Science Chapter Heredity and Evolution, Heredity and Evolution NCERT Solutions

When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.

Outline a project which aims to find the dominant coat colour in dogs.

Draw the structure for the following compounds.                

       (i)    Ethanoic acid             (ii)   Bromopentane*
       (iii)  Butanone                   (iv)   Hexanal.

*Are structural isomers possible for bromopentane?

A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?

How is the sex of the child determined in human beings?

(a)  What property do all elements in the same column of the Periodic Table as boron have in common?
(b)  What property do all elements in the same column of the Periodic Table as fluorine have in common?

Calculate the number of electrons constituting one coulomb of charge.

A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?

What is an homologous series? Explain with an example.

Why is variation beneficial to the species but not necessarily for the individual?

Describe sexually transmitted diseases and mention the ways to prevent them.

Name the plant hormones responsible for the following
(a) elongation of cells
(b) growth of stem
(c) promotion of cell division
(d) falling of senescent leaves.

Where should an object be placed in front of a convex lens to get a real image of the size of the object?

(a) At the principal focus of the lens
(b) At twice the focal length
(c) At infinity
(d) Between the optical centre of the lens and its principal focus.

How will an organism be benefited if it reproduces through spores?

Distinguish between a gamete and zygote. Explain their roles in sexual reproduction.

What is the role of the seminal vesicles and the prostate gland?

Explain the importance of soil for plant growth.

What are various ways to avoid pregnancy? Elaborate any one method.

The kidneys in human beings are a part of the system for

   (a) nutrition.                  (c) excretion.
   (b) respiration.              (d) transportation.

Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?