control and coordination



In animals, the maturation of gonads and activity of spermatogenic tissue are also temperature dependent, which varies from species to species. In blow fly, Calliphora sericate, the number of eggs laid per Female, increases with increase in temperature upto 32.5(after which the number decreases. similarly, in chrotogonustrachypterus(an acridid insect),egg Laying increases from 25 to 300C.Thus,temperature also affects the fecundity(reproductive capacity)of animals. Similarly, an increase in temperature from 22 to 320C increases the egg laying about 20-30 times in Melanopussanguinipes.

Growth and Development: In Ostrea virginea, the length of body increases from 1.5 to 10.3 mm with an increase in temperature from 10 to 200C.

Thermoregulation and homeostasis: The birds and mammals have constant Body temperature and are called homeothermal or endothermic or warm blooded animals to deal with temperature extremes. This is achieved through evaporation of water from their bodies during summer and through Insulating action of fur, feathers, fats, etc.

what is Collenchyma

Collenchyma is made up of living cells which are usually elongated with thick corners. There is absence of intercellular spaces in this tissue. Few chloroplasts are present in the cell of Collenchyma. The Collenchyma occurs in layers below the epidermis in dicotyledonous plants.

It consists of cells which are much thickened at the corners due to a deposition of cellulose, hemicellulose and pectin. These cells assimilate food when they contain chloroplasts. Inter cellular spaces are absent. They provide mechanical support to the growing parts of the plant such as young stem and petiole of a leaf.

  1. It provides mechanical strength to young dicot stem, leaves etc.
  2. It also provides flexibility to the organ and allows their bending.
  3. It prevent tearing of leafs.



A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. The particles in suspensions are bigger than 100 nm to 200 nm across. The particles of a suspension may not be visible to the naked eye but are visible under a microscope. Such as: Milk of magnesia is a suspension of magnesium hydroxide in water.


  • Suspensions are heterogeneous systems.
  • They stay only for a limited period. i.e. these are not stable as the particles have a tendency to settle down under the influence of gravity.
  • The particles of a suspension can neither pass through ordinary filter paper nor through animal membranes. Examples of suspensions are sodium chloride in benzene, turmeric in water, silver chloride, barium sulphate or sand in water.

Class 11th, biology, ch. – 3, part – 1

ANGIOSPERM (Flowering plants)

These are the most advanced plants, characterized by the presence of flower, covered ovules and seeds. Angiosperms are the largest group of plants on Earth. There are approximately 270,000 known species alive today. There’s probably one nearby right now. These form the largest group of the plant kingdom, containing about 300 families, 8000 genera and about 300,000 species. These are the highest evolved plants on this earth. From cretaceous period, the angiosperms eclipsed all other vegetation and now they are the most dominant plants. They are found almost everywhere in all possible habitats. Angiosperms include all varieties of plants such as hydrophytes, xerophytes, epiphytes, parasites, saprophytes, insectivorous, symbionts and mangroves etc.

Characteristic features of angiosperms

  1. Presence of flower is the most striking feature of angiosperms. It contains the sex organs of the plant.
  2. Ovules are covered and are present inside the ovary.
  3. Pollen grains are received by the stigma of the carpel, so maturation of pollen grain (male gametophyte) takes place on stigma.
  4. Double fertilization (syngamy and triple fusion) is also characteristic only to angiosperms.

What is Internet?

Internet is a means of communication where people sitting in different parts of the world can talk to each other through their computers.

Internet is actually a network of computers. Any kind of message or information like words, pictures, music etc. can be digitized and converted into a series of electrical signals called bits through the internet. It is then sent through the telephone line to another computer which convert these bits back into the message.

Respiration part – 1


The process of releasing energy from food is called Respiration. It involves taking in O2 into the cells, using it for releasing energy by burning food and then eliminated the waste products from body of human. It is essential process for life because it provides energy for carrying out the entire organism alive.

Breathing and Respiration

  • The mechanism by which organism obtain O2 from air and release CO2 is called as breathing. While respiration includes breathing and oxidation of food in cells of organism to release energy.
  • Breathing is physical process while respiration is a biochemical process that requires many enzymes.
  • Breathing involves with the lungs. While the respiration involves with the mitochondria of cells where food is oxidised.
  • Respiration is just opposite to the photosynthesis. Because photosynthesis makes food by using CO2, water and sunlight and releasing O2 where as respiration breaks food (like glucose) by using O2 and release CO2, water and energy.
  • Energy produced during respiration is stored in the form of ATP molecules in the cell of body of human.
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