FOOD CHAINS

FOOD CHAINS: A food chain is a linear relationship between producers and consumers.
It represents the transfer of food energy from green plants through repeated stages of eating and being eaten.
Types of Food Chain
Grazing food chain – starts with green plants.
Detritus food chain – starts with dead organic material (debris or detritus).

ECOLOGY

Introduction

Ecology is the study of organisms and their environment.
All organisms show interdependence on one another.
Organisms are affected by their environment, and they in turn affect the environment.
Green plants manufacture food by photosynthesis which other organisms obtain directly or indirectly.
Growth of plants is mainly affected by environmental factors such as soil and climatic factors.
On the other hand, organisms modify the environment through various activities.
This interrelationship comprises the study of ecology.

BIOLOGY PRACTICAL ACTIVITIES

To examine Bryophyta

A mature moss plant is obtained.

The specimen is observed using a hand -lens.
A labelled drawing showing structures is made: rhizoids, set a capsule, gametophyte, sporophyte.

To examine Pteridophyta

A mature fern plant is obtained.
It is observed using a hand lens.
Sori can be seen on the lower side of fronds.
A labelled drawing showing: frond, pinna, sorus, rhizome and adventitious roots.

CHARACTERISTICS OF VERTEBRATES

Bees are important in pollination i.e. in production of honey

Members of the phylum have a notochord in early stages of development.
They have visceral clefts – which are slits perforating the body wall at the pharynx.
In fish these slits become gills while in higher chordates these slits are only present in embryo.
They have a dorsal, hollow nerve cord.
It develops into a brain at the anterior and spinal cord at the posterior end.
The spinal cord is enclosed within the vertebral column.
They have segmented muscle blocks known as myotomes on either side of the body.
They possess a post-anal tail although rudimentary in some.
They have a closed circulatory system.
The heart is ventrally located.
They possess an internal skeleton.

KINGDOM FUNGI

Multicellular fungi are made of thread-like structures called hyphae (singular hyphae) that form a mycelium. e.g. Saccharomyces cereviseae (bread yeast).
Others include Penicillium, Rhizopus, and edible mushroom

Economic Importance of Fungi

Beneficial Effects

Some fungi are used as food e.g. mushrooms.
Some are decomposers which enhance decay to improve soil fertility – recycling of nutrients e.g., toadstools.

KINGDOM PROTOCTISTA

Examples include;

Algae such as spirogyra, Chlamydomonas, euglena, Sargassum
And protozoa such as amoeba, paramecium and Trypanosoma.

General Characteristics

They are said to be eukaryotic since their nucleus is bound by a membrane
Most are mobile, and use flagella, cilia and pseudopodia.
Some are sessile.
They reproduce mainly asexually, by binary fission, fragmentation and sporulation.

GENERAL PRINCIPLES OF CLASSIFICATION IN BIOLOGY

Classification is the science that puts organisms into distinct groups to make their study easy and systematic.
Modern scientific classification is based on structure and functions.
Organisms with similar anatomical and morphological characteristics are placed in one group while those with different structures are grouped separately.
Modern studies in genetics and cell biochemistry are used to give additional help in classifying organisms.

JAUNDICE (SKIN AND EYES)

This is a yellow colouration of the skin and eyes.

Cause: 

Presence of excess bile pigments.
This happens due to blockage of bile duct or destruction of liver.

Symptoms: Yellow pigmentation of skin and eyes, nausea, vomiting and lack of appetite. Itching of skin.

Treatment

Removal of stones from the gall bladder by surgery.
Give patient fat-free diet, reduced amount of proteins.
Give antihistamines to reduce itching.

LIVER EXCRETION

Role of Liver in Excretion

The liver lies below the diaphragm and it receives blood from hepatic artery and hepatic portal vein.
Blood flows out of the liver through hepatic vein.
Excretion of Nitrogenous Wastes
Excess amino acids cannot be stored in the body; they are deaminated in the liver.
Hydrogen is added to amino group to form ammonia which combines with carbon (IV) oxide to form urea.

STRUCTURE AND FUNCTIONS OF THE KIDNEYS

The kidneys are organs whose functions are excretion, osmoregulation and regulation of pH.
Kidneys are located at the back of the abdominal cavity.
Each kidney receives oxygenated blood from renal artery, while deoxygenated blood leaves through the renal vein.
Urine is carried by the ureter from the kidney to the bladder, which temporarily stores it.
From the bladder, the urine is released to the outside via the urethra.

EXCRETION AND HOMEOSTASIS (PLANT AND ANIMAL)

Introduction

Excretion is the process by which living organisms separate and eliminate waste products of metabolism from body cells.
If these substances were left to accumulate, they would be toxic to the cells.
Egestion is the removal of undigested materials from the alimentary canals of animals.
Secretion is the production and release of certain useful substances such as hormones, sebum and mucus produced by glandular cells.
Homeostasis is a self-adjusting mechanism to maintain a steady state in the internal environment

DISEASES OF THE RESPIRATORY SYSTEM

Asthma

Asthma is a chronic disease characterized by narrowing of air passages.

Causes:

Allergy

Due to pollen, dust, fur, animal hair, spores among others.
If these substances are inhaled, they trigger release of chemical substances and they may cause swelling of the bronchioles and bring about an asthma attack. Heredity
Asthma is usually associated with certain disorders which tend to occur in more than one member of a given family, thus suggesting’ a hereditary tendency.

GASEOUS EXCHANGE IN A MAMMAL

The breathing system of a mammal consists of a pair of lungs which are thin-walled elastic sacs lying in the thoracic cavity.
The thoracic cavity consists of vertebrae, sternum, ribs and intercostal muscles.
The thoracic cavity is separated from the abdominal cavity by the diaphragm.
The lungs lie within the thoracic cavity.
They are enclosed and protected by the ribs which are attached to the sternum and the thoracic vertebrae.