Lesson Note on Biology SS2 Second Term
SCHEME OF WORK
WEEK 1 EXCRETION
WEEK 2 TISSUES AND SUPPORTING SYSTEMS
WEEK 3 COMPONENTS OF THE MAMMALIAN SKELETON
WEEK 4 JOINTS
WEEK 5&6 ALIMENTARY CANAL/DIGESTIVE SYSTEM
WEEK 7 FEEDING HABITS
WEEK 8 FEEDING IN AMOEBA, HYDRA AND MAN
WEEK 9 TRANSPORT SYSTEMS
WEEK 1O CIRCULATORY SYSTEM IN MAMMALS
WEEK 11 MECHANISM OF TRANSPORT IN HIGHER PLANTS
SS2 Second Term Biology Lesson Note
Below are the 2022 complete SS2 Second Term Biology Lesson Note
Topic: Excretory System
Every organism, from the smallest protist to the largest mammal, must rid itself of the potentially harmful by-products of its own vital activities.
Excretion is the removal of waste products from the chemical reactions that occur inside all living things (organisms). In other words, excretion is the removal of harmful and unwanted toxic waste products of metabolism. To learn more, Click here.
Topic: Supporting Tissues and Systems
Living organisms including plants and animals need tissues to enable them carry out life processes such as movement, respiration, etc. For example, without the various bones and tissues, vertebrates may not be able to stand, respire, move and carry out their life processes.
Skeleton is the bony framework of the body which provides support, shape and protection to the soft tissues and tissues in animals.
The human skeleton consists of 206 bones. We are actually born with more bones (about 300), but many fuse together as a child grows up. The longest bone in our bodies is the femur (thigh bone). The smallest bone is the stirrup bone inside the ear. Each hand has 26 bones in it. Your nose and ears are not made of bone; they are made of cartilage, a flexible substance that is not as hard as bone. To learn more, Click here.
Topic: Vertebrate Skeleton
The skeleton of vertebrates is composed primarily of bone. Cartilage covers articular surfaces between bones and connects the ribs to the sternum. The skeleton is divided into two major parts:
1. The axial skeleton includes the skull, mandible, hyoid, ribs, sternum, and vertebrae
2. The appendicular skeleton includes the girdle, limb and feet bones. To learn more, Click here.
The human skeleton consists of more than 200 bones. The individual bones are attached in such a way that a large variety of coordinated movements are made possible in different parts of the body. These movements are made possible by skeletal muscles, the fact that the bones act as levers, cartilage which reduces friction and ligaments which prevent dislocation and the presence of movable joints. The site or place where two or more bones of the skeleton are attached to each other is called a joint or place of articulation.
A joint or place of articulation is formed where two or more bones come in close contact in the body and are attached to each other by ligaments. To learn more, Click here.
Topic: Digestive System
The digestive system or alimentary canal or tract is concerned with the breakdown of complex food substances and its conversion in to simpler components, its absorption through the bloodstream and assimilation in the cells and tissues producing desired effects of growth. Digestion is the breakdown of food into smaller components that can be more easily absorbed and assimilated by the body. We have two types of alimentary tracts, namely, the complete and incomplete alimentary tract.
· The incomplete tract has just an opening into the outside world which is referred to as the mouth. This serves the purpose of ingestion and egestion. An example of an organism with an incomplete alimentary tract is a planarian. To learn more, Click here.
Topic: Feeding Habits
Modifications and Mechanisms of Feeding in some Animals
There are five modifications and mechanisms of feeding associated with some organisms. These feeding mechanisms include:
Absorbing Mechanisms, e.g. tapeworm
The tapeworm is an endoparasite which carries out parasitic feeding on its host i.e., the man. It has no mouth but absorbs digested food from the intestine of its host. The body of the tapeworm is modified and adapted for parasitic feeding as follows:
- The alimentary canal is absent, hence food is absorbed through its entire body surface
- The tapeworm has hooks and suckers which are used for attachment to the intestine of the host to avoid dislodgement
- The body has thick cuticle which resists the digestive enzymes of the host
- The flat body surface of the tapeworm provides a large surface area for the absorption of already digested food. To learn more, Click here.
Topic: Feeding in Amoeba, Hydra and Man
Amoeba feeds on microscopic organisms such as single-celled algae and bacteria. When the amoeba encounters a suitable organism, the cytoplasm flows round the prey and engulfs it, with a drop of water, in a food vacuole. The cytoplasm secretes enzymes into the food vacuole. The enzymes digest the soft parts of the prey and the soluble products are absorbed back into the cytoplasm. Any undissolved residue is left behind as the amoeba flows on.
Feeding in Hydra
Hydra feeds on a variety of small aquatic animals, such as Daphnia and Cyclops, which it catches by means of lots of tiny stinging cells on its tentacles. Scattered over the outer layer tentacles are a great many of these stinging cells called cnidoblasts. Smaller numbers occur on the main body. Each cnidoblast contains a capsule (nematocyst) from which projects a small “trigger” called a cnidocil. Inside each capsule is a tiny hollow thread. It is inverted like a finger of a glove which is pushed into the hand part. These threads are the food-catching apparatus. To learn more, Click here.
Topic: Transport Systems
Organisms need to be able to move materials such as respiratory gases, nutrients, waste products and heat both into and out of, and within its body.
A transport system is a means by which materials are moved from an exchange surface or exchange surfaces to cells located throughout the body system.
Specialized exchange surfaces are biological structures whose features are such that they permit the highly efficient transfer of materials e.g. respiratory gases, across them via mechanisms such as diffusion or active transport. Although many micro-organisms accept materials directly through their cell membrane. To learn more, Click here.
Topic: Circulatory System In Mammals
Circulatory system refers to the continuous movement or flow of blood round the body involving the heart and the blood vessels.
Higher organisms e.g. man, require blood to carry materials to and from different parts of their body. There is need for organisms to transport oxygen from the lungs to other living cells within the organisms and also, dissolved food materials absorbed in the villi to other parts of the body which need them. Circulation is the process by which absorbed food materials are carried through arteries, capillaries and veins to all parts of the body where they are utilized for body functioning. Materials which are transported by blood in human body are water, salts, hormones, oxygen, digested food, etc. waste materials also removed from the body through blood circulation. To learn more, Click here.
Topic: Transport System in Plant
In a simple plant like an alga, materials enter or leave the cells in the body by diffusion. In higher land plants, special conducting tissues, known as vascular tissues carry out transport.
Two main types of vascular tissue are used in transport – xylem and phloem.
·Xylem transports water and minerals.
·Phloem transports organic molecules such as the products of photosynthesis. To learn more, Click here.