SS 2 Biology (1st, 2nd & 3rd Term)

REPRODUCTIVE SYSTEM Most multicellular animals and plants undergo a complex form of sexual reproduction in which especially differentiated male and female reproductive cells (gametes) unite to form a single cell, known as a zygote, which later undergoes successive divisions to form a new organism. The process takes place with the help of the system known

This is the transfer of mature pollen grains from the anther of one flower to the mature stigma of the same or another flower of the same plant or another plant of closely related species. Pollination usually precedes fertilization. There are two types of pollination namely, self-pollination and cross-pollination. SELF POLLINATION This is the transfer

PROTECTIVE FUNCTION OF BLOOD The blood performs two basic functions in mammals and these are: (1) Transportation of various substances and (2) Protection of the body against diseases The blood defends the body in major ways Antibody production (Clumping): The lymphocytes produce antibodies which are any of a large variety of proteins normally present in

INVERTEBRATES Feeding in Hydra Digestion in Planaria Digestion in Earthworms Digestion in insects (Grasshopper) VERTEBRATES Digestion in Birds Digestion in Rabbits FEEDING IN HYDRA Hydra feeds on small aquatic organisms e.g. crustaceans. It captures its food through its structure called nematocysts found on its tentacles. The food is then passed into the mouth while the

hen population-influenced factors (abiotic and biotic) are favourable, growth is promoted but when they are unfavourable growth is retarded.

The orderly change in the inhabitants of an area over time is called succession. It can also be defined as the step by step orderly and gradual replacement of communities of organisms that leads to a climax community. An illustration of succession is that of a pond. Rain carries sediment from surrounding land into the

STRUCTURES AND FUNCTIONS OF THE REPRODUCTIVE ORGANS IN PLANTS The flower is the reproductive structure of a flowering plant. It has both male and female sex organs hence it can carry out sexual reproduction. After fertilization has taken place in flowers, seeds are produced. A flower has two major parts: The floral part (whorls) The

Excretion is the process by which metabolic waste products are removed from the body of all living things. Excretion is different from egestion which is the removal of solid waste (undigested food substances i.e.faeces) through the anus. Excretion is necessary for the following reasons: To avoid or prevent any harm that would be caused by

POLLUTION  Definition: Pollution is defined as the release of toxic or harmful substances into the environment by their natural forces or man and other animals to an extent that causes biological damage to man and his resources. In other words, pollution is the release of harmful substances into the environment, i.e., water, air and land

DEFINITION/PHASES OF RESPIRATION The process of respiration involves the taking in of oxygen its transport within the body of the organism, its exchange in the cells and the eventual release of energy in form of ATP, water and carbon(IV)oxide. The energy is utilized by the cells for their daily activities. Respiration can therefore be defined

Nitrogen Cycle Nitrogen is an abundant element in the atmosphere. It is an essential constituent of proteins, a group of substances found in all living cells. About 78% of air is composed of gaseous nitrogen. Plants cannot incorporate nitrogen gas into organic compound and therefore depend on various types of bacteria to make nitrogen available

In simple unicellular plant materials are exchanged by simple diffusion process between the plants and its aquatic environment. Hence there is no need for elaborate transport system. However, in higher plant such as ferns and the flowering plants. There is a need for elaborate transport system for transporting water and mineral salts from the soil

RESPIRATORY SYSTEM IN MAMMALS The respiratory system of mammals is the most complex of all respiratory systems. It comprises a pair of lungs enclosed in the thorax and connected to the outside by a series of branched air tubes. In human beings, air can be drawn in through the mouth or nose. Both lead into

To carry out life processes, all organisms (plants and animals) need tissues. Tissues are group of similar cells that carry out specific functions. Skeleton is the framework of the body which provides support, shape and protection to the soft tissues and organs in animals. It forms the central core of human body and it is

HABITAT (AQUATIC HABITAT) Habitat is a place where organisms (plants, microorganisms and animals) are naturally found e. g. the habitat of tadpole is the bottom of fresh water ponds or streams. There are three main types of habitats, namely; aquatic habitat (in or around water), terrestrial habitat (in or on land) and arboreal habitat (in

ADAPTATION Adaptation is defined as the ability of an organism to live successfully in a particular habitat as a result of its structure, appearance and behaviour. It is expected that every organism must adapt to its environment in order to survive. Plants and animals possess certain features which enable them to adapt to either aquatic