Test: Science-4

​In humans, each cell normally contains 23 pairs of chromosomes, a total of 46. 

​The strongest muscle based on its weight is the masseter. With all muscles of the jaw working together, it can close the teeth with a force as great as 55 pounds (25 kilograms) on the incisors or 200 pounds (90.7 kilograms) on the molars. 

​A heart attack-medically was known as a myocardial infarction. The symptoms of heart attack include; pain or discomfort in one or both arms, back, neck, jaws or stomach. Shortness of breath with or without chest discomfort other signs such as breaking out in a cold sweat, nausea of lightheadedness. As with men and women’s most common heart attack symptom is chest pain or discomfort. 

​Blood is a liquid connecting tissue. It flows inside the blood vessels and is viscous thick fluid. 

​Plants use only certain colours from light for the process of photosynthesis. The chlorophyll absorbs blue, red and violet light rays. Photosynthesis occurs more in blue and red light rays and less or not all in green light rays. 

​Fats have highest calorie value per unit because of its higher rate of oxidation due to less oxygen.

Cloves are the aromatic closed, dried floral bud, which is used in Ayurvedic medicine, making food and as an anodyne for dental emergences. 

​Hydrophytes or an aquatic plants are plants, that have adapted to live in an aquatic environment (salt water of fresh water). 

​Mendel’s principle of inheritance is based on sexual reproduction. 

Leprosy is caused by a slow-growing type of bacteria called Mycobacterium leprae (M. leprae). 

​The number of rings indicates the number of years the tree lived. 

​Antony Van leeuwenhoek is regarded as the father of microbiology. He is known for the discovery of bacteria. 

​Cactus, calotropis, aloe, etc. are desert plants which have the capability to complete their life-cycle even in a dry atmosphere. The root system of these plants become taller in search of water from the soil and their stems are small, adapted and underground sometimes. 

​Gene mapping is the method used for determining the location of gene and relative distances between genes on a chromosome. The essence of all genome mapping is to place a collection of molecular markers onto their respective positions on the genome. Molecular markers come in all forms. Genes can be viewed as one special type of genetic markers in the construction of genome maps and mapped the same way as any other markers. 

Red blood cells (RBCs) or red blood corpuscles also called erythrocytes are the most common type of blood cell and he vertebrate organism’s principal means of delivering oxygen (O_2) to the body tissues-via blood flow through the circulatory system. RBCs take up oxygen in the lungs or gills and release it into tissues while squeezing through the body’s capillaries. The cytoplasm of erythrocytes is rich in haemoglobin, an iron-containing biomolecule that can bind oxygen and is responsible for the red colour of the cells. 

​Calcium Oxalate is a chemical compound that forms envelope shaped crystals, known in plants as raphides. A major constituent of human kidney stones is calcium oxalate. 

Progesterone hormones are related to uterus and menstrual cycle of female. Testosterone is secreted by testis of male. Thyroxine is secreted by thyroid gland. Insulin is secreted by pancreas. 

The deficiency of iodine causes goiter in which the neck becomes thicker. Anemia is caused by iron deficiency. Vitamin A & B are useful to prevent night blindness and beri-beri respectively. 

​Skin cancer is caused due to presence of excess arsenic in water.