• Mitosis results in the production of diploid daughter cells with identical genetic complement usually.
• Cell divides by mitosis to restore the nucleo-cytoplasmic ratio.
• Helps in cell repair.
• Mitotic divisions in the meristematic tissues result in a continuous growth of plants throughout their life.

Characteristic features of Phylum Ctenophora:

i. They show biradial symmetry and are triploblastic.

ii. They are characterized by the presence of eight rows of cilia that help in locomotion.

iii. Ctenophores possess sticky cells called colloblasts to capture prey.

iv. They lack skeletal, respiratory or excretory system.

Examples : Hydra, Tubularia, Bougainvillea, Hydractinia, Eudendrium, Pennaria, Obelia, Sertularia, Plumularia

Red-tides: Red tides are caused by the red dinoflagellates (Gonyaulax) that multiply rapidly in sea and impart it a red colour. They release large amounts of toxins in water that can cause death of a large number of aquatic animals.

Monocot plants have leaves that are characteristically longer and slender. Stomata in monocot leaves are dumb-bell shaped. Monocot leaves are amphistomatic – which means the stomata are present on lower as well as the upper surface

The cell theory states as:

- All living organisms are made up of living cells

- Cell is the basic structural and functional unit of living organisms.

- All new cells arises from the pre-existing cells

There are many other scientists who contributed in the making of cell theory including Rudolph Virchow who contributed a lot.

Photolysis is the splitting of water molecules in the presence of light into proton, electron and oxygen. It takes place during non-cyclic photophosphorylation. The protons are used to reduce NADP and electrons are fed to photosystem II. The splitting or decomposition of a chemical compound by means of light energy or photons. Supplement. For example, the photolysis of water molecule in photosynthesis occurred under the influence of light. When photons are absorbed, it causes the hydrogen to bind to an acceptor, subsequently releasing the oxygen.

Adipose tissue is a specialized connective tissue consisting of lipid-rich cells called adipocytes. As it comprises about 20-25% of total body weight in healthy individuals, the main function of adipose tissue is to store energy in the form of lipids (fat). Adipose tissue is commonly known as body fat. It is found all over the body. It can be found under the skin (subcutaneous fat), packed around internal organs (visceral fat), between muscles, within bone marrow and in breast tissue.

The classification of living things includes 7 levels: kingdom, phylum, classes, order, families, genus, and species. The most basic classification of living things is kingdoms. Currently, there are five kingdoms. A large variety of plants, animals, and microbes found on earth and differ in size, shape, colour, habitat, and many other characteristics. So, studying each of them is impossible. Therefore, scientists have devised mechanisms to classify all living organisms on certain rules and principles that allow identification, nomenclature, and finally classification of an organism.

A frog will eat just about any living thing he can fit in his mouth, but he also has sensitive taste buds. He will occasionally spit out hastily grabbed prey if the taste is unpleasant. The taste buds are on the surface of his tongue and the inside of his mouth. Completely aquatic frogs in the Pipidae family do not have tongues, but they have taste discs in their mouth tissue to receive taste sensations. Osmoreceptors present in the mouth of frog are involved in detecting osmotic pressure and maintain the salt and water balance in the body fluids. Male recognises a mature female by swollen abdomen.

1. Organise and classify - the organism can be easily categorised, this really helps making it easier to understand the characteristics of a specific organism in an organised chart.

2. Clarity and precision - these names are unique with each creature having only one scientific name. Helps avoid confusion created by common names.

3. Universal recognition - scientific names are standardised and accepted universally.

4. Stability - the names are retained even if the species are shifted to another genera based on new knowledge.

5. Inter specific relationship - binomial terms help understand the similarities and differences between different species belonging to the same genera, useful in establishing a relationship between the two.

Anabaena azollae maintains a mutually beneficial symbiotic relationship with the water fern Azolla, which provide the cyanobacteria with a safe environment in exchange for nitrogen. Azolla is grown in tropical and temperate climates in calm bodies of water.

ollowing are the important functions of the hypothalamus:

• Its main function is maintaining the body’s internal balance- homeostasis.
• It also connects the endocrine and the nervous system.
• Hypothalamus stimulates or inhibits many of the body’s activities in order to maintain homeostasis, such as regulating body temperature, appetite and body weight, heart rate and blood pressure, etc.
• It is involved in many essential functions of the body, including:

1. Childbirth.
2. Emotions.
3. Sleep cycles.
4. Balancing body fluids.
5. Appetite and thirst control.
6. Blood pressure and heart rate.

Metabolism is the total amount of the biochemical reactions involved in maintaining the living condition of the cells in an organism. All living organisms require energy for different essential processes and for producing new organic substances.

The metabolic processes help in growth and reproduction and help in maintaining the structures of living organisms. The organisms respond to the surrounding environment due to metabolic activities. All the chemical reactions occurring in the living organisms from digestion to transportation of substances from cell to cell require energy.

Living things are made up of cells and are capable of carrying out various cellular activities. The different features that best describe what a living thing is, are mentioned below:

• Growth is usually defined by the increase in mass and number of individual organisms. Humans visibly grow up to a certain age, but the cells keep on dividing and thus new cells in the body keep on replacing the old ones.
• Reproduction is the process by which an organism produces an individual like its own.

• Cilia and flagella are hair-like outgrowths of the cell membrane.
• Cilia and flagella help in cell movement.
• Core of cilia and flagella is called the axoneme, possesses a number of microtubules running parallel to the long axis.
• The axoneme usually has nine pairs of doublets of radially arranged peripheral microtubules, and a pair of centrally located microtubules. Such an arrangement of axonemal microtubules is referred to as the 9+2 array.
• The central tubules are connected by bridges and is also enclosed by a central sheath, which is connected to one of the tubules of each peripheral doublets by a radial spoke and hence there are nine radial spokes.
• The peripheral doublets are also interconnected by linkers.
• Both the cilium and flagellum emerge from centriole-like structure called the basal bodies.

During interphase a number of changes take place so as to prepare the cell for division. During this period, the cell experiences growth and DNA replication.

The interphase is divided into three phases, which are as follows:

(i) G1 phase (Gap 1): During this phase, the cell is metabolically active and continuously grows and prepares its DNA for replication.

(ii) S phase (Synthesis): During this phase, DNA synthesis or replication takes place. In this phase, the amount of DNA per cell doubles, but the number of chromosomes remain the same.

(iii) G2 phase (Gap 2): During this phase, proteins and RNA synthesis take place so to prepare the cell for mitosis. The cell growth continues during this phase.