The H.S.B. syllabus:
 SECTION A – Living Organisms and the Environment;
 SECTION B – Life processes;
 SECTION C – Heredity and Variation;
 SECTION D – Diseases and its impact on humans;
 SECTION E – The impact of health practices on the environment.
FORMAT OF THE EXAMINATION
Paper 01 (1 hour 15 minutes) Sixty multiple-choice items.
Paper 02 (2 hours)
Section A - four compulsory structured questions. Each question is worth 15 marks.
Section B - two compulsory structured essay questions. Each question is 15 marks.
Paper 032 (1 hour 15 min) Alternative to S.B.A. for private candidates only. Tests research
skills based on a given Case Study.

Lesson A-1:
 Characteristics of living things;
 Cells;
 Movement of substances by diffusion, osmosis and
active transport;

Objectives:
 describe the characteristics of living organism;
 compare the structures of an unspecialized plant and animal
cell and selected microbes;
 state the functions of cell structures;
 identify selected cells which make up the human body;
 explain the importance of cell specialization in humans;
 distinguish between osmosis, diffusion and active transport;
 explain the importance of osmosis, diffusion and active
transport in living systems.

Characteristics of living organisms(GRIMNER)
Growth - increase in size and development.
Respiration –process whereby living organisms obtain energy from food.
Irritability (Sensitivity) – ability to detect and respond to stimuli from the
surroundings.
Movement – moving parts of the body or moving from place to place
(locomotion).
Nutrition – making own food (plants) or consuming available food (animals).
Excretion - getting rid of waste produced in cells.
Reproduction – producing offspring.
https://www.youtube.com/watch?v=ZMoc3IjxEks&t=905s

Unspecialized plant and animal cells:
 All living organisms are made up of cells.
 Organisms can be unicellular (made up of a single cell) or multicellular
(made up of many cells)
 Both plant and animal cells have certain common structures such as: a
nucleus, cytoplasm, cell membrane, mitochondria and ribosomes.
 A plant cell also has: a cell wall, chloroplasts and a large vacuole.

Cell organelles:

Unicellular organisms:

Cell specialization:
Multicellular organisms contain a large number of cells, which have
different shapes, different number of organelles and perform different
functions. This is called cell specialization.

Specialised cells in the human body:

Cell differentiation:
 In order for a cell to become
specialised, a process called
differentiation occurs, where
unspecialised cells (called stem
cells) produce cells with
specialised structures.
 All multicellular organisms contain
some form of stem cells. These are
mostly the cells that divide to
replace damaged or old tissue, or
new cells for growth.

Levels of organisation:
CELLS → TISSUES → ORGANS → ORGAN SYSTEMS → ORGANISM
 Cells: the smallest units that can carry on all the
processes of life.
 Tissue: a group of cells with similar structures,
working together to perform a shared function.
 Organ: a structure made up of a group of tissues,
working together to perform specific functions.
 Organ system: a group of organs with related
functions, working together to perform body functions

The four basic types of animal tissue:
Epithelial tissue: forms the skin and the outer
and inner lining of organs. .
Connective tissue: consists of collagen fibers,
ground substance and cells which connect,
support and bind other tissues.
Muscle tissue: muscle cells connect together in
sheets and fibers which contain contractile
proteins that contract to produce movement.
Nervous tissue: forms the nervous system. It
consists of neurons and supporting cells called
neuroglia and is responsible for coordinating and
controlling body functions.

Organ systems in the human body:

Movement of substances in/out of cells:
 Diffusion is the net movement of molecules and ions from a region of
higher concentration to a region of lower concentration , as a result of
their random movement.

Diffusion in the human body:

Osmosis:
 Osmosis is the diffusion of water molecules through a selectively
permeable membrane from a higher water potential (less
concentrated solution) into a lower water potential (more
concentrated) solution.

Osmosis:

Effects of osmosis on animal and plant cells:
 Hypotonic solution: less
concentrated than
inside cells;
 Hypertonic solution:
more concentrated than
inside cells;
 Isotonic solution: same
concentration as inside
cells.

Active transport:
 Active transport is the movement of ions or molecules across a cell
membrane from a region of low concentration to a higher
concentration region. This requires energy (stored in ATP molecules)
and is assisted by a carrier membrane proteins and enzymes.

Examples of active transport in humans
and plants:
 The sodium/potassium pump of cells: Pumps Na+ ions from the cytoplasm (lower
Na+ concentration) to the extracellular space (higher Na+ concentration). At the
same time, K+ ions are pumped in the opposite direction also against their
concentration gradient.
 Intestinal absorption of glucose and aminoacids: glucose and aminoacids are
transported from the intestinal lumen (lower concentration) into epithelial cells of
the villi (higher concentration) by an active transport mechanism called co-transport,
whereby membrane proteins carry them at the same time they transport Na+ ions
into the epithelium.
 Selective reabsorption of nutrients in the kidneys: glucose, aminoacids, vitamins, etc,
move from the renal tubules of the nephrons (lower concentration) into the
surrounding blood capillaries (higher concentration).
 Intake of dissolved mineral ions by root hair cells in plants.

Importance of diffusion, osmosis and active
transport:
 Diffusion allows for the gaseous exchange required for respiration and
photosynthesis to take place. It is the way most nutrients enter the cells and waste
products are removed.
 Osmosis facilitates the distribution of essential nutrients in the body and the
excretion of metabolic waste products. It also regulates the solute concentration
within cells and balances the pressure of intra and extracellular fluids. It is by
osmosis that plants uptake water from underground which is needed for
photosynthesis, translocation of nutrients and transpiration.
 Active transport is required for carrying molecules and ions across cellular
membranes against their concentration gradient. It is involved in essential vital
processes such as the intestinal absorption of nutrients, the reabsorption of
nutrients in the kidneys and the uptake of mineral ions by plants.