CBSE Class X – Science Biology Exam ( Full Syllabus)

Acquired traits are the changes which do not occur in the DNA of the individual or in its genes thus they are not passed from one generation.

The maleness of a child is determined by the presence of the Y chromo-some in the zygote inherited from the father.

Radish and carrot represent the correct homologous structures because both have similar design or structure, though both are of different species.

The cross between RR yy and rr YY seeds will obtain RrYy ofspring which will exhibit round and yellow phenotype, as these traits are the dominant ones.

If we dig into the earth and start fnding fossils, the fossils we fnd closer to the surface are more contemporary than the fossils we fnd in deeper layers.

The pair of sex chromosomes is odd as it is not a perfect pair. Women have a perfect pair of sex chromosomes, both called XX while men have a mismatched pair in which one is a normal sized X and the other is a short one called Y.

formation of single cell during sexual reproduction by fusion of nuclei of male and female gamates.

After the pollen lands on a suitable stigma, a tube grows out of the pollen grain and travels through the style to reach the female ovary.

Sexual reproduction involves fertilisation of male and female gametes to produce zygote having genetic variations. Clones cannot be produced through it as clones are identical copies of parent organism.

Menopause is a natural process at the age of 40s or 50s in case of human females. Menopause occurs when a women has not have her menstrual cycle for 12 consecutive months and can no longer become pregnant naturally.

The lime water turns milky on passing carbon dioxide gas into it due to formation of insoluble calcium carbonate. When the exhaled air rich in carbon dioxide is blown from mouth into test tube, it reacts with lime water (calcium hydroxide) to produce calcium carbonate and water

Digestion of food starts in mouth by salivary amylase. From here it enters into the stomach via oesophagus The simpler substances formed by chemical digestion are then absorbed by small intestinal villi.

During inhalation, the air is drawn through the nostrils into the nasal passage. From there, air enters into pharynx, larynx, trachea (windpipe), bronchi, lungs and fnally to the alveoli.

Among the given options, Amoeba (binary fssion), Yeast (budding) and banana (vegetative propagation) reproduce by asexual reproduction whereas dogs reproduce by sexual method.

Living organisms are well organised structures; they can have tissues, tissues have cells, cells have smaller components in them, and so on. Living creatures keep repairing and maintaining their structures

The opening and closing of the pore is a function of the guard cells. The guard cells swell when water fows into them, causing the stomatal pore to open. Similarly, the pore closes if the guard cells shrink.