BIOLOGY NOTES FOR ADVANCED LEVEL – Form 5 and 6

BIOLOGY NOTES FOR ADVANCED LEVEL

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IMPORTANCE OF HAVING A BALANCED DIET

A
balanced diet is the combination of different food items consumed together to
get a balanced proportion of all the nutrients required by the body. A proper
balanced diet includes all the essential meals of the day. It provides a
different amount of proteins, carbohydrates, fats, vitamins, etc.

Here are
some benefits of a Balanced Diet:

1. Improved Physical Health

Eating
a balanced diet can help maintain a healthy weight, lower the risk of chronic
diseases like diabetes, heart
disease, and certain cancers, and improve the immune system’s
function.

2. Lower
Risk of Obesity and Heart Disease

A balanced daily menu along with
portion control and timing of meals eliminates excessive sugar overload in the
bloodstream, reduces insulin spikes, and prevents dangerous levels of
inflammation. Inflammation in our bodies is the cause of so many
illnesses including obesity, heart disease, diabetes, and autoimmune
disorders like multiple sclerosis, Alzheimer’s disease, and Parkinson’s
disease.

3. Increased Energy Levels

A
balanced diet gives the body the nutrients that are required to function at its
best, leading to increased energy levels and improved productivity.

4. Fight Off Disease

When
eating a balanced diet, essential nutrients will produce and help maintain key
germ-fighting cells in the immune system, and greatly improve vascular
function. The immune system relies heavily on blood flow, so better vascular
function will help provide disease fighting cells to areas of need quickly.
Deficiencies in certain nutrients can impair immune system function, such as
vitamin A, B-vitamins, vitamin C, vitamin E, Zinc, and Iron. A diet filled with
fruits and vegetables also increases the production of infection-fighting white
blood cells and materials that help prevent bacteria and infections from
attaching themselves to cells in the body.

5.  Better Sleep 

A
varied, balanced daily menu sends signals to your body that it is in a safe
nourished place which decreases stress and allows for quality sleep at
night. When we don’t fill our bodies with sugar and processed foods with
dangerous and addictive ingredients we allow our bodies to use sleep to do the
housekeeping that our bodies require on a daily basis. When we are
constantly having to process unhealthy foods throughout the whole day we give
our bodies less of a chance to heal at night.

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CELL STRUCTURE AND ORGANIZATION

The Concept of Cell

The Meaning of the Cell

Explain the meaning of the cell

Plants and animals are made up of units called cells. The cells are microscopic in such a way that they cannot be seen by our naked eyes. Some organisms like protozoa, diatoms and bacteria consist of one cell and are called single-celled or unicellular organisms. Some are made up of many cells and are called multicellular organisms.

The cell structure of living things was first seen by Robert Hooke in 1667 when he examined fine slices of cork. Robert Hooke believed that the cells were empty and that the cell wall and cell membrane were the most important parts of the cell but now cell contents are seen to be the most important ones. Therefore a cell can be defined as the smallest unit of living things or a cell is a basic unit of life.

The Characteristics of the Cell

Mention the characteristics of the cell

Characteristics of the cell include the following:

1. Cells are small microscopic structures which cannot be seen by our naked eyes.
2. Cells are capable of dividing by mitotic process or meiotic process.
3. Cells contain structures called organelles.

The cell theory

1. A cell is a basic unit of structure and function in living organisms.
2. New cells only come from pre-existing ones.
3. Cells contain structures called organelles.

The cell theories were proposed jointly by two scientists namely Schleiden, a Belgian botanist, in 1838 and Schwann, German Zoologist, in 1839

Difference Between Various Types of Cells

Differentiate various types of cells

PROKARYOTIC AND EUKARYOTIC CELLS

Prokaryotic cells are cells with no membrane-bound nucleus. The DNA lies free in the cytoplasm in a region known as nucleoid. They have no true nuclei. Examples of prokaryotic organisms are bacteria.

Eukaryotic cells are cells whose nuclei are bounded by nuclear membrane. They are surrounded by two nuclear membranes called nuclear envelope. Examples of eukaryotic organisms are protoctists, fungi, plants and animal cells.

Differences between cell wall and cell membrane

Different between prokaryotic and Eukaryotic cells

The Functions of Different Parts of Plant and Animal Cells

Explain the functions of different parts of plant and animal cells

Basically a cell has three main parts

1. Cell membrane
2. Cytoplasm
3. Nucleus

Cell membrane (plasmalemma)

This is a thin flexible membrane made of protein and oil. It has the following functions:

1. The cell membrane encloses the contents of the cell.
2. It is freely permeable to water and gases only and selectively permeable to other molecules e.g. it allows food in but keeps unwanted molecules out. Thus cell the membrane controls the substances entering and leaving the cell.

Cytoplasm

Cytoplasm is a transparent jelly-like fluid and may contain particles such chloroplasts or starch grains or oil droplets. It contains up to 80% water and the remainder is mainly protein. It is a place where chemical reactions take place

Nucleus

A nucleus is a ball-shaped or oval body located inside the cytoplasm. It cannot usually be seen unless the cell has been stained with certain dyes. It consists of nucleoplasm bounded by nuclear membrane. The nucleus is a cell control centre.

The following are the functions of the nucleus:

1. It controls the formation and development of a cell.
2. The nucleus also controls chemicals which the cell manufactures.
3. The nucleus contain chromosomes which carry genetic material i.e. DNA which is responsible for controlling genetic information.

Cell wall

The cell wall is only found in plant cells. It is made up of cellulose. When the cell is growing the cell wall is fairy plastic and extensible. It becomes tough and resists stretching when the cell has reached full size. The cell wall is non-living. It has the following functions:

1. It gives the cell its shape.
2. It is freely permeable to all kinds of molecules.
3. It supports and protects the cell.
4. It supports non-woody plant organs, such as leaves, by turgor pressure.
5. It osmoregulates by resisting entry of excess water into cell.

Vacuole

In animal cells, vacuoles are small droplets of fluid in the cytoplasm variable in size and position. In plant cells, the vacuole is a large, permanent fluid-filled cavity which occupies a greater part of the cell. In plants, the fluid is called cell sap. The cell sap may contain salts, sugar and pigments dissolved in water.

The vacuole performs the following functions:

1. It is responsible for food storage and osmoregulation.
2. The outward pressure of the vacuole on the cell wall makes the plant cells firm, giving strength and resilience to the tissues.

Mitochondria

Mitochondria are found in all aerobic eukaryotic cells. A mitochondrion is surrounded by an envelope of two membranes, the inner being folded to form cristae (singular: crista) It contains a matrix with a few ribosomes, a circular DNA molecule and phosphate granules.

Mitochondrion

A mitochondrion is a power house of a cell. It contains respiratory enzymes involved in respiration. It absorbs oxygen and glucose. The glucose is broken down to CO₂ and H₂O. Energy is released from glucose bonds to form ATPs (for use in other vital functions e.g. growth, movement, etc.

Chloroplast

Chloroplasts are disc-shaped organelles. They are found in plant cells and algae cells. A chloroplast contains a green substance called chlorophyll. It is surrounded by an envelope of two membranes and contains gel-like stroma through which runs a system of membranes that are stacked in places to form grana.

Chloroplast

Chloroplast is an organelle in which photosynthesis takes place, producing sugars from carbon dioxide and water using light energy trapped by chlorophyll.

Golgi body

Golgi bodies are stacks of flattened, membrane-bound sacs

Golgi bodies have the following functions:

1. Golgi bodies are responsible for internal processing and transport system.
2. Processing of many cell materials e.g. protein takes place in the cisternae.
3. Godgi vesicles transport the materials to the other parts of the cell

Plant and Animal Cell

Draw and label plant and animal cell

Animal cell

Plant cell

Similarities and Differences of Plant and Animal Cells

Outline similarities and differences of plant and animal cells

Differences between plant cell and animal cells

Similarities between animal cell and plant cells

1. Both have cell membranes
2. Both contain cytoplasm
3. Both have nucleus
4. Both have mitochondria
5. Both have golgi bodies
6. Both have ribosomes

Cell Differentiation

The Concept of Cell Differentiation

Explain the concept of cell differentiation

When most cells have finished dividing they become specialized. This means that:

• They do one particular job
• They develop a distinct shape
• Special kinds of chemical change take place in their cytoplasm

The changes in shape and chemical reactions enable the cell to carry out its special function. The process by which cells are specialized to perform a particular function is called cell differentiationor ‘division of labour’ within the organism. Similarly, the special functions of mitochondria, ribosomes and other cell organelles may be termed as division of labour within the cell.

The Importance of Cell Differentiation and Formation of Tissues, Organs and Body Systems

Outline the importance of cell differentiation and formation of tissues, organs and body systems

Humans have many different types of cells with different jobs, such as blood cells that carry oxygen and nerve cells that transmit signals to all parts of the body. Cell differentiation is the process by which cells become specialized in order to perform different functions.

Even multicellular organisms begin as just a single cell. Getting from one single cell to billions of specialized cells that perform different functions is a process that happens with the regulation of DNA and RNA. It can also be influenced by factors in the environment.

Cell differentiation holds a lot of importance for two basic reasons. Firstly, it helps to identify stem cells, which could be used in the future to deal with conditions that require transplant and form the basis of embryonic stem cell research. Also, in cytopathology, the level of cellular differentiation is used as a measure of cancer progression, where the term ‘grade’ is used as a marker to determine how differentiated a cell in a tumor is. Thus, the importance of this process cannot be underestimated as it could hold the key to future treatments for fatal diseases.

Difference between Cells, Tissues Organs and Body Systems

Differentiate cells, tissues organs and body systems

Animal cells

Nerve cells

These are specialized for conducting impulses of an electrical nature along the fibre. The fibre may be very long e.g. from the foot to the spinal column. They are the longest cells known.

Nerve cell

Blood cells

• White blood cells:These cells occur in blood stream and are specialized for engulfing harmful bacteria. They are able to change their shapes and move about, even through the walls of blood vessels into the surrounding tissue.

White blood cell

• Red blood cells:These cells are responsible for transportation of oxygen from the lungs to all parts of the body.

Red blood cells

• Platelet cells: Platelet cells are found in the blood. They are also called blood platelets. Their function is to help clot the blood at wounds and so stop bleeding.

Reproductive cells

• Sperm cell: it is a male gamete produced in the testes.

Sperm cell

• Egg cell:It is a female gamete produced in the ovary.

Egg cell

Muscle cells

These are elongated cells which form the muscle tissues. Muscle cells are highly specialized in that they are able to shorten a half or even a third of their resting lengths. This characteristic enables the muscles to contract and expand.

Muscle cell

Ciliated cells

These cells form the lining of the nose and wind pipe.

Plant cells

Root hair cells

These cells form the outer layer of young roots. The cells are specialized to absorb water and mineral slats from the soil. The hair-like projections penetrate the soil particles and offer a large absorbing surface.

Phloem cells

These are food conducting cells in a plant, joined end to end, and where they meet, perforations occur in the walls. Through these holes, the cytoplasm of one cell communicates with the next.

Xylem cells

The cells conduct water and mineral salts form the soil to all parts of the plant. They are also responsible for mechanical support.

• Parenchyma cells
• Collenchyma cells
• Sclerenchyma cells
• Epidermal cells

TISSUES

A tissue is a group or collection of similar cells performing a specific function. Tissues vary in size, shape and function.

Examples of tissues

Animal tissues

Animal tissues include epithelial tissue, muscle tissue, nervous tissue, blood tissue and bony tissue.

Epithelial tissue: Epithelial tissues cover the body lining cavities, hollow organs and tubes. They are responsible for (i) protection of the underlying structure from dehydration, and chemical and mechanical damages; (ii) secretion; and (iii) absorption.

Muscle tissue

Muscle tissue consists of cells specialized to contract and move the body. Muscle tissues can be:

1. skeletal muscle tissue;
2. smooth muscle tissue; or
3. cardiac muscle tissue.

Skeletal muscle tissues form those muscles that move the bones

Smooth muscle tissues

These are found in the walls of hollow organs. They perform the following functions:

• Regulate the diameter of blood vessels and parts of the respiratory tract.
• Propel the contents of the ureters, ducts of glands and alimentary tract.
• Expel contents of the urinary bladder and uterus.

Smooth muscle fibres

Cardiac muscle tissue

This kind of muscle tissue is found only in the heart wall. It helps in contracting and relaxing of heart muscles thus pumping the blood to various body parts.

Nervous tissues

Nervous tissues have endings that detect changes in the environment. They transmit and conduct nerve impulses to the brain and spinal cord and to the effector organs.

Plant tissues

Examples of plant tissues are collenchyma tissue, sclerenchyma tissue, epidermal tissue, conducting tissues e.g. phloem and xylem, palisade tissue and spongy tissue.

An onion epidermal tissue

Plant organs

Examples of plant organs include leaves, stems, roots, flowers and fruits

Organ system

A system refers to several inter-related organs performing a particular function.

Digestive system

The main organs that make up the digestive system are alimentary canal, liver and pancreas.The main function of this system is to digest and absorb food.

Circulatory system

This system consists of the heart, arteries and veins.The role of the circulatory system is to transport gases, food, hormones and distribute heat.

Lymphatic system

Lymphatic system has comprises of the lymph vessels and lymph nodes. The main function of the lymphatic system is to transport materials and protect against.

Respiratory system

The respiratory system consists of the trachea and the lungs. The role of the respiratory system is to take in oxygen and expel carbon dioxide gas.

The urinary system

The main organs of the urinary system are kidneys, ureter, bladder and urethra.The urinary system plays a role in removing metabolic waste products from the body and also it is responsible for osmoregulation.

The urinary system

The nervous system

This system consists of the brain, spinal cord and nerves.The role of the nervous system is to detect and respond to stimuli.

The muscular system

It consists of the organs muscles and tendons. The role of the muscular system is to bring about movement.

The skeletal muscles

BALANCE OF NATURE

The Natural Environment

The Concept of Natural Environment

Explain the concept of natural environment

Natural environment is made up of all living and non living things that occur naturally on earth. An organism living anywhere in any environment is affected by the things around it such as air, water, animals, plants, microorganism, stones, rock, soil, clouds and the sun. everything around it in fact makes its natural environment. It is important to understand that the environment includes all living things as well as non living things.

IMPORTANT TERMS

1. Ecology: is the branch of biology that deals with studying interaction oforganisms with their environment
2. Population: is the total number of organisms of the same species living in a certain area. Example the number of frogs in a pond
3. Community: this refers to the sum of total of all population of different organisms living in a specific called habitat
4. Habitat: is the specific area where an organism is found and adopted. i.e it is an appropriate for the certain community example an ocean, grassland, and a pond
5. Ecosystem: refers to a natural unit made up of living and non living things whose interaction

Biotic and Abiotic Components of the Environment

Describe biotic and abiotic components of the environment

There are two components of environment,;

1. Biotic (living things)
2. Abiotic (non living things)

BIOTIC COMPONENT

These are living components in the environment such as animals, plants, fungi, and microorganisms. These organisms interact together in number of ways and these ways of interaction include the following;

1. Competition That organisms must compete for limited resources in struggle for life. For an organism to survive in an ecosystem it must compete with partner for the limited resources.
2. Predation Is the system in which one organism utilize the other as food. The eater is a predator while the eaten is a prey and a number of predators and preys regulate each other
3. Symbiotic relationship This is where there is a close relationship or association between organisms this association could take various forms like mutualism, commensalism, and parasitism
4. Adaptation Adaptation has enabled organisms to survive. They may be anatomically structurally physiologically or behavioural. Eg some organisms are poisoners to their predator while others while others develop warming colouration

ABIOTIC COMPONENTS

These include non living organisms that are found in ecosystem. Example air solar, energy, soil, and nutrients. Generally abiotic components of an ecosystem consist of physical environment and they are as follows.

1. Climatic factor Several change of climatic condition influence or determine the survival of organisms in ecosystem such condition include temperature, humidity, pressure etc
2. Aquatic condition Changes in the aquatic environment and the nature of environment it is self determined by the type of organism found in the area such a changes include water current, wave action, salinity, etc
3. Light condition factor These affect much plant population where photosynthetic process depend on the availability of light.
4. Soil factor/condition. These are also adaphic factors and they include soil texture, soil structure and soil PH

The Importance of the Natural Environment

Explain the importance of the natural environment

IMPORTANCE OF NATURAL ENVIRONMENT

1. It is a source of food to organisms
2. It provides shelter and security for organisms
3. It allow living and non living things to interact
4. It provides an appropriate setting for organisms to reproduce and increase in number.

Interactive of Organisms in the Environment

Ways in Which Living Organisms Interact with the Non Living Component of the Environment

Identify ways in which living organisms interact with the non living component of the environment

The following are the interaction of organism in the environment

1. Ground water and water from rain flow into streams and rivers
2. The stream and rivers flow into lakes and ocean
3. Water evaporate into the atmosphere from lakes and ocean and from plants through transpiration
4. The evaporated water precipitates to form water vapor which condenses to form clouds
5. Wind causes clouds to move for example from above the ocean to above the land
6. Rain fall and absorbed by plants or form grounds water, and the cycle begins again..

The Interaction of Organisms among Themselves

Explain the interaction of organisms among themselves

INTERACTION AMONG LIVING ORGANISMS

1. CompetitionThat organisms must compete for limited resources in struggle for life. For an organism to survive in an ecosystem it must compete with partner for the limited resources .EXAMPLE lions and leopards both hunt zebra, and so they are competitors
2. PredationIs the system in which one organism utilize the other as food. The eater is apredator while the eaten is a prey and a number of predators and preysregulate each other. e,g cats eat mice
3. SymbiosisThis is where there is a close relationship or association between organisms this association could take various forms like mutualism, commensalism, and parasitism
4. Mutualism is a relationship where two organisms benefit each other for example the rhizobium bacteria in the root nodules of legumes fix nitrogen into nitrate to ne used by the plant
5. AdaptationAdaptation has enabled organisms to survive. They may be an atomically structurally physiologically or behavioural. Eg some organisms are poisoners to their predator while others while others develop warming coloration
6. Commensalism is the interaction that is beneficial to one organism and is neutral to the other organism. For example when a bird builds a hole or a nest in a tree
7. Parasitism is the association where one organism benefit while the other is harmed. E.g plasmodium that cause malaria to human

Food Chain and Food Web

The Meaning of Food Chain and Food Web

Explain the meaning of food chain and food web

FOOD CHAIN

Is the sequence of living things in which each organism is the food of the next in thesequence.

1. 1. Grass →Zebra→Lion
2. Maize plant→grasshoppe→rFrog

→

FOOD WEB

Is made of interconnecting food chains

The Components of a Food Chain and Food Web

Mention the components of a food chain and food web

Producers

Are organism that can manufacture their own food for example green plants and green bacteria

Primary consumers

They are organisms that feed on producers for example rabbits, buffalo andsheep

Secondary consumer

They are organisms that feed on primary consumer

Decomposers

These organisms feed on dead matter and break it down thereby facilitating decomposition. For example bacteria and fungi

The Difference between Food Chain and Food Web

Distinguish food chain from food web

Differences between food chain and food web

Diagrammatic Representation of a Food Chain and Food Web

Construct a diagrammatic representation of a food chain and food web

Food chain

Food chain example

1. Grass →cow→human being
2. Phytoplankton→fish→bird

Food we

The Significance of Food Chain and Food Web in Real Life Situation

Explain the significance of food chain and food web in real life situation

The following are the significant of food chain and food web

1. Food chains and webs help in the flow of energy from producers to consumers and from one trophic level to another, without which energy flow would be impossible.
2. Food chain studies have had an important role in ecotoxicology studies tracing path ways and biomagnifications of environmental contaminants.
3. Learning how the food chain works enable us to understand the importance living organisms that make up the food chain and how the ecology is balanced. This is crucial since any interruption in food chain could lead to ecosystem imbalance.
4. Food chains and webs show the flow of energy through an ecosystem.
5. Understanding the effect of polluting the natural environment enable us to avoid or control environme

CLASSIFICATION OF LIVING THINGS

Kingdom Fungi

Member of the kingdom Fungi include fairly familiar organisms such as mushrooms, toadstools and bracket fungi. There are also less obvious but very important members such as mold, which grow on bread, ripe fruits and other food.

The General and Distinctive Features of the Kingdom Fungi

Explain the general and distinctive features of the kingdom Fungi

General features of kingdom fungi

1. Fungi are found in damp or wet places
2. They have eukaryotic cells with a rigid protective wall made of chiti
3. They are heterotrophs, some are saprophytic where others are parasitic
4. They store food as glycogen
5. They reproduce using spore
6. They are non-mobile

Distinctive features of kingdom fungi

1. They have chitin in their cell wall
2. They have septate

The Phyla of the Kingdom Fungi

State the phyla of the Kingdom Fungi

Phyla of the kingdom fungi

1. Ascomycota
2. Zygomycota
3. Basidiomycota

Ascomycota

Ascomycota are also called sae fungi. They produce spore in sae-like cell called asei. These spores are called ascopores. Examples of Ascomycota are bakers’ yeast, cup fungi and ring worm fungi.

Characteristics of phyla Ascomycota

1. Their cell wall is not made by chitin but cetin polysaccharide component of phosphoric acid
2. Have granulated cytoplasm
3. Store food in form of glycogen
4. Reproduce asexually by budding and sexually by means of ascospores.

Distinctive features

1. Reproduce sexually by means of ascospores

(i) Reproduce sexually by means of ascospores

The Structure of Mosses

Describe the structure of mosses

Mosses are small, soft plants called bryophytes, that are typically 1–10 cm (0.4–4 in) tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems. At certain times mosses produce spore capsules which may appear as beak-like capsules borne aloft on thin stalks.

Advantage and Disadvantages of Mosses

Outline advantage and disadvantages of Mosses

On the advantage side, it can help to hold the bonsai soilin place and prevent it from washing out of the container. Moss can increase the water retention capability of the soil by slowing evaporation.

On the disadvantage side, a thick carpet of moss can reduce the diffusion of gases into the soil and to the roots, which can result in root rotor poor drainage conditions. Moss can grow up onto the surface roots and trunk of your bonsai, and soften their bark, promoting its decay.

Division Filicinophyta (Pteridophyta)

General and Distinctive Features of the Division Filicinophyta

Explain general and distinctive features of the division Filicinophyta

This division was formerly called Pteridophyta. The division Filicinpphyta includes a group of primitive vascular plants. The adult plant body in these plants is a sporophyte. It shows differentiation into true roots, stems and leaves. The stem is mostly herbaceous. Leaves may be smaller or larger. Vascular tissues are present in all the vegetative parts of the plant body.

Characteristics of division Filicinophyta

Members of this kingdom include horsetails, ferns and mosses.

1. Reproduction involves production of spores inside special structures called sporangiawhich occur on the underside of the leaves called sporophylls. Sprangia may sometimesbe found in groups called sori.
2. The plants may be homosporous – producing only one type of spore or heterosporous -producing two different types of spores; smaller microspores and larger megaspores.
3. They are seedless vascular plants, which contain vascular tissues but do not produceseeds.

The Structure of Ferns

Describe the structure of Ferns

Ferns are intermediate in complexity between the more primitive bryophytes (mosses, liverworts, and hornworts) and the more advanced seed plants. Like bryophytes, ferns reproduce sexually by making spores rather than seeds. Most ferns produce spores on the underside or margin of their leaves. Like seed plants, ferns have stems with a vascular system for efficient transport of water and food. Ferns also have leaves, known technically as megaphylls, with a complex system of branched veins.

In general, ferns consist of the following structures:

Fronds

The frond is the “leaf” of a fern. It is divided into two main parts, the stipe (leaf stalk or petiole)and the blade (the leafy expanded portion of the frond).