Role of Sun in the origin and evolution of life on earth: The Sun played a very vital role in the origin of life and its evolution on earth as is evident from the following- In the initial stages of the origin of life on earth, the chemicals such as carbon, hydrogen, oxygen and nitrogen
Racemose Inflorescence: In this type of inflorescence, the main axis does not end in a flower, but it grows continuously and develops flowers on its lateral sides in acropetal succession (i.e the lower or outer flowers are older than the upper or inner ones). The various forms of racemose inflorescence may be described under three
Differences Between Blood and Lymph: Following are the points of differences between Blood and Lymph. Blood Lymph It is a red coloured fluid. It is a colourless fluid. Blood is opaque. It is almost transparent. Water content is nearly 55%. Water content is nearly 94%. Blood is quite viscous. Viscosity is about 4.7. It is
Birds have adapted themselves to an aerial mode of life: Birds have evolved from reptiles during the course of evolution. It is on this account that the birds are sometimes referred to as glorified reptiles. If we see the shape, structure and appearance of the body of birds, we see that every part, organ and
Fertilization is Physico-Chemical process: The penetration of sperm into the ovum, during the process of fertilization, involves a series of physio-chemical events. As the spermatozoa pass through the male genital passages, they undergo a process of maturation. During the process of maturation, spermatozoa acquire some motility only after passing through the epididymis. The secretions of
Respiratory organs present in human being: Nasal Cavity: Nasal Cavity is a hollow structure partitioned into two nasal chambers by the nasal septum. It is composed of cartilage, bone, connective tissue and muscles. There are pairs of openings situated at the anterior and posterior ends of the nasal chambers. The anterior nostrils lead to the
What is Skeletal System? The hard parts of an animal body present inside or outside the body collectively form the skeletal system or Skeleton. Types of Skeleton: Skeleton is of two types- Exoskeleton and Endoskeleton. Exoskeleton: It is protective and supportive framework present outside the body. An exoskeleton is made up of hard structures or
What is Reproduction? Reproduction is the formation of new young ones by the grown-up individuals so as to produce a new generation or progeny. Members of the new progeny or generation are broadly similar to their parents except for size. Basic Features of Reproduction: All modes of reproduction have some common basic features. These are
Phases of Biological Evolution of Life: After the formation of complex macromolecules and nucleoproteins which are actually supposed to be the building molecules of a living system, further events in relation to the origin of life constitute the biological evolution of life which includes the following phases- Origin of Primordial Life: It is believed that
Hormones Secreted by the Adrenal Cortex are the following- Mineralocorticoids: These are the steroid hormones secreted by the outermost cellular layer (zona glomerulosa) of the adrenal cortex. The fundamental mineral corticosteroid is aldosterone. Its secretion occurs when there is a fall in plasma sodium concentration or rise in plasma potassium. They control electrolyte and water
