CBSE Class X – Science Biology Exam ( Full Syllabus)

In human beings, sex of the individual is genetically determined as the genes inherited from our parents decide whether we will be boys or girls.

The size of the body is an acquired trait because it depends on nutritional status, health conditions, etc. It can change depending on the Components like availability of less or more food.

One pair called the sex chromosomes is odd, not always being a perfect pair. Women have a perfect pair mismatched pair, in which one is a normal-sized X while the other is a short one called Y (XY).

The two versions of a trait which are brought in by the male and female gametes are situated on copies of the same chromosome. Each parent contributes one copy of the gene for a particular trait.

The tendril of a pea plant and the phylloclade of Opuntia are homologous structures, as they are modifed stems but serve diferent functions in diferent plants.

Reduction division (meiosis) takes place during gamete formation.

Bread mould prefers damp/warm conditions with ample nutrient supply, on which air-borne spores land and germinate.

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.

Unisexual flowers contains only one reproductive organ, either male or female.

Rice water contains starch, hence when iodine solution is added to rice water it turns blue-black.

Valves prevent backward fow of blood as they are located at each end of two ventricles and act as one way inlet.

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.

During inhalation, the ribs move out and the diaphragm fattens. As a result, the surface area for gaseous exchange increases. The site for gaseous exchange in the lungs are alveoli._x000D_During inhalation, ribs move inward and diaphragm is raised_x000D_In the alveoli, exchange of gases takes place i.e. oxygen form alveolar air difuses into blood and carbon dioxide from blood into alveolar air._x000D_Haemoglobin has greater aǝinity f or carbon dioxide than oxygen_x000D_Alveoli increases surface area for exchange of gase

The anterior vena cava collects deoxygenated blood from the head, chest, and arms and enters the right atrium while the inferior vena cava collects blood from the lower body regions_x000D__x000D_Left atrium receives oxygenated blood from diferent parts of body while right atrium receives deoxygenated blood from lungs_x000D_Left ventricle pumps oxygenated blood to diferent body parts while right ventricle pumps deoxygenated blood to lungs_x000D_Left atrium transfers oxygenated blood to right ventricle which sends it to diferent body parts_x000D_Right atrium receives deoxygenated blood from diferent parts of the body while left ventricle pumps oxygenated blood to diferent parts of the body

The examples and the relation of animal group and heart are as Fishes have two chambered heart and exhibit single circulation while three chambered heart of amphibian and reptiles and four chambered heart of birds and mammals exhibit double circulation.

Fishes have only two chambers to their hearts, and the blood is pumped to the gills, is oxygenated there, and passes directly to the rest of the body. Thus, blood goes only once through the heart in the fsh during one cycle of passage through the body.

Xylem tissues include tracheids, vessels, fbres and parenchyma and serve in the ascent of sap/water and minerals.