SCIE 3001
1 - Nature of Living Things
1.4 Human Organ Systems and Health
4 - Cycles and Seasons
5 -Structure of the Earth, and Earth Movements

Unit 1 - Living Things

Nature of Living Things

This section introduces you to:

  1. Classification of living things
  2. Development and growth of living things
  3. Energy and living things
  4. Human organ systems and health

Some people have difficulty telling the difference between living, dead, and non-living things. Five hundred years ago, many people believed that nonliving things could spontaneously turn into living things. For example, it was believed that piles of straw could turn into mice or maggots developed from food. Louis Pasteur's work on the link between bacteria and disease founded the science of microbiology and proved that most infectious diseases are caused by micro-organisms. People then beganto understqand the "germ theory" of disease. He was the inventor of the process of pasteurisation and also developed vaccines for several diseases including rabies.

So developed the understanding of the separation of living (biosphere) and non-living words (geosphere, hydrosphere and atmosphere). Over time scientific knowledge acknowledged some general differences between living and non-living things. It is interesting that as scientific knowledge evolves, these differences are becoming more blured.

Living things are:

  1. made of cells.
  2. obtain and use energy (respiration).
  3. obtain and use nutrients (nutrition).
  4. grow and develop (growth).
  5. reproduce (reproduction).
  6. respond to their environment (sensitivity).
  7. produce and eliminate waste products that may be toxic (excretion)
  8. sometimes able move from one place to another (locomotion)
  9. adapt to their environment.

A single individual or even a group of living things may not show all of the above characteristics. Something may follow one or just a few of the characteristics listed above and is still not necessarily living. To be considered alive, an individual object or the group it belongs to must exhibit most of the characteristics of living things.

1. Answer this question - Are the following living?

  • Crystals growing on the bottom of a saturated solution...
  • A car breathing in oxygen and burning fuel to move.
  • Using a fuel like coal in a stove to produce energy.
  • A motion sensor turning on lights.
  • Waste products being eliminated into the environment by an industrial plant.

2. Do some research to make notes on these characteristics described above.

Nature vs Behaviour

It is clear that behaviour of living things can be mimiced by non living thigs as as technology increases, it is becoming increasingly difficult to tell living from non-living in this modern world. One way to do so is to look at the nature of living things - how they are built.

Cells can b e seen as "the building blocks of life". All life, from the simple like bacteria to the complex like human beings, are made up of cells. However, despite their apparent differences, the major groups represented by plants and animals are made up of cells that actually possess maany of the same structuress.


Plant and animal cells have:

  1. Nucleus: the cell's 'command center'. It regulates the various metabolic processes within the cell and contains most of the cell's genetic material (DNA), is usually located near the center of animal cells, and closer to the edge in plants.
  2. Cell Membranes: This layer surrounds and protects the contents of the cell. It allows certain molecules to pass through it and enter the cell, while preventing others from so doing (selectively permeable).
  3. Cytoplasm: The fluid which inside the cell. Organelles are suspended in the cytoplasm.
  4. Mitochondria: the powerplant' of the cell. It converts food into energy. The number of mitochondria is an indicator of the activity level of the cell. So plant cells tend to have fewer mitochondria than animal cells. Mitochondria also contain a small amount of DNA, and therefore play a role in genetics.
  5. Golgi Bodies: location where substances are processed and carried to the proper location within the cell, or out of the cell altogether.
  6. Vacuoles: These are sacs which serve as storage units. Vacuoles in animal cells are tiny, and are used to carry substances out of the cell, or to engulf undesirable substances such as bacteria or bits of dead tissue. In plant cells, there are usually only one large vacuole which acts as a storage tank for food, water, waste products and other materials.

Primary Differences Between Plant and Animal Cells

Plant cells:

  1. produce their own food in the chloroplasts by a process called photosynthesis to use the energy of sunlight to convert carbon dioxide and water into food. The chloroplasts contain chlorophyll that gives many plants their green colour.
  2. have a rigid cell wall which helps support their weight. Many animals usually do this by means of a skeleton.
  3. have a cell wall on the outside of the cell membrane, which together with the central vacuole helps the cell maintain shape and rigidity.
  4. have a large central vacuole, which when filled with water helps to keep the cell rigid because of the water pressure against the cell wall . As vacuoles loose water a plant wilts.
cell wall plant   outer layer
rigid, strong, stiff
made of cellulose
support (grow tall)
allows H2O, O2, CO2 to pass into and out of cell
cell membrane plant animal plant - inside cell wall
animal - outer layer

selectively permeable - controls movement of materials in/out of cell
support protection- barrier between cell and its environment

nucleus plant animal large, oval controls cell activities
cytoplasm plant animal clear, thick, jellylike material and organelles found inside cell membrane supports /protects cell organelles
mitochondrion plant animal bean-shaped with inner membranes breaks down sugar molecules to release energy
Golgi Bodies plant animal stacks of flattened membranous sacs substances are processed and carried to the proper location within the cell, or out of the cell altogether
vacuole plant animal fluid-filled cavities store food, water, waste (plants need to store large amounts of food)
chloroplast plant   green, oval usually containing chlorophyll (green pigment) uses energy from sun and water and carbon dioxide to make food for the plant

Reproduction in plants

Life cannot exist without plants.

There are three methods of reproduction in plants:

  1. From seeds.
  2. From spores.
  3. Vegetative propagation (from body parts)

A seed has two main parts:

  1. Seed coat: Protective covering which protects the baby plant inside the seed. It has a tiny hole through which the seed gets water.
  2. Seed leaves or cotyledons: They contain food for a growing baby plant.

Germination is the development of a seed into a seedling (baby plant). The seed needs oxygen, water and warmth (sunlight) for germination.

Stages of growth

  1. Seed absorbs water from the soil.
  2. Seed coat becomes soft and it breaks up and the baby root (radicle) emerges followed by the baby shoot (plumule).
  3. Root grows down into the soil.
  4. Baby shoot develops and grows towards the sunlight.
  5. Tiny leaves appear on the shoot. As the leaves grow, they start making their own food (photosynthesis).
  6. The new plant produces flowers which grow into fruits.
  7. Fruits contain seeds.
  8. Given suitable condition of air, water and warmth, these seeds germinate and grow into new plants.
  9. In this way the cycle of reproduction in plants continues.

Dispersal of seeds

  1. Seeds need to be scattered away from the mother plant.
  2. Dispersal of seeds is accomplished by agents like air, water, animals, birds, human beings and explosion.
  3. Dispersal helps the seeds to reach the suitable place where they get enough air, water and warmth needed for their germination. It prevents the competition of seeds growing near the mother plant.

Agents of dispersal

  1. Wind Seeds of cedar, mahogany and maple are light. They may have wings or hair which help them to move away to far-off places with wind.
  2. Coconuts are hollow and float in water.
  3. Animals and human beings eat fruits and throw away their seeds. Some seeds stick to the bodies of animals as they have hooks, thorns or stiff hair. Animals swallow some seeds and these seeds are passed out in their droppings.
  4. Explosion Fruits of sandbox and balsam burst open when dry. Their seeds are flung away with a great force.

From spores

Plants like fern and mosses reproduce through spores. These are called non-flowering plants and do not have fruits and seeds. They spores germinate under suitable conditions and grow into new plants.

Vegetative propagation

Some plants grow from body part like root, stem, leaves, etc. This type of reproduction in plants is called vegetative propagation.

Groups of Animals

Sorting animals into groups is called classifying.

All organisms are split into five Kingdoms:

Animal Kingdom: organisms that usually move around and find their own food.

The two main groups of animals are vertebrates and invertebrates. Vertebrates are all animals with a backbone or internal bones.


  1. Chordate Phylum: All the animals which have a backbone. Includes: Fish, Reptiles, Birds, Amphibians, and Mammals.


  1. Arthropod Phylum: All the "jointed legged" animals. All of these animals have an exoskeleton, meaning the skeleton is on the outside of the body. Include: Insects, Arachnids, and Crustaceans.
  2. Mollusk Phylum: Soft-bodied animals that sometimes have a hard shell. Includes: Snails, Slugs, Octopus, Squid, Clams, Oysters, and Mussels.
  3. Annelid Phylum: Segmented worms. Includes: Earthworms and Leeches.
  4. Rotifer Phylum: Tiny, microscopic animals with a wheel-shaped mouth and tiny hairs.
  5. Nematode Phylum: Very tiny worms with no segments in their bodies. Also called Roundworms.
  6. Tardigrade Phylum: Tiny, slow-moving animals with four body segments and eight legs. Includes Water Bears.
  7. Cnidarian Phylum: Soft-bodied, jelly-like animals with tentacles and venom glands. Includes: Hydra, Jellyfish, Anemones, and Coral.
  8. Echinoderm Phylum: Often spiny animals, with several "arms" reaching out from the center of its body. Includes: Starfish and Sea Urchins.
  9. Platyhelminthes Phylum: Soft, flat-bodied worms. Includes: Planarians and Tapeworm

Plant Kingdom: organisms that make their own food and do not actively move around.

  1. Magnoliophyta Division: All "flowering" plants. These plants have leaves, stems, and roots. After flowering, they form fruits with seeds. Includes most crops, trees, shrubs, grasses, garden plants, and weeds.
  2. Coniferophyta Divsion: Plants that bear cones. Includes: Pine Trees and Cedars.
  3. Pteridophyta Division: Plants that have roots and stems, but do not have flowers or seeds. Instead, they spread with spores. Includes Ferns.
  4. Bryophyta Division: Plants with very small leaves and stems, with no roots and no flowers. Usually grow very low to the ground. Includes: Mosses.
  5. Lycopodiophyta Division: Small plants with green, branched stems, scale-like leaves, and no flowers. Usually grow very low to the ground. Includes: Club Mosses, Quillworts, and Spikemosses.

Fungi Kingdom: organisms that absorb food from living and non-living things.


Protist Kingdom: organisms that have single, complex cells.

Moneran Kingdom: organisms that have single, simple cells.

  1. Bacteria Phylum: These organisms are extremely important and can also be very dangerous. They live anywhere there is moisture, including inside animal's bodies. Some carry disease.
  2. Cyanobacteria Phylum: These organisms are also known as Blue-green Algae. These algae are different from the Green Algae found in the Plant Kingdom.


Parts of the Flower

Flowers are important in producing seeds. While flowers can be different, there are some parts that are found in many flowers. The main flower parts are the male part called the stamen and the female part called the pistil.

The stamen has two parts: anthers and filaments. The anthers produce the pollen. These are often yellow in color and are held up by a thread-like part called a filament.

Pistil: The pistil has three parts: stigma, style, and ovary. The ovary often supports a long style, topped by a stigma. The stigma is the sticky surface at the top of the pistil - it traps and holds the pollenwhere it germinates. The style is the tube-like structure that holds up the stigma. The style leads down to the ovary that contains the ovules.The mature ovary beecomes the fruit, and the mature ovule a seed.

Ovary: The enlarged basal portion of the pistil where ovules are produced.

Pedicel: The stalk of a flower.

Receptacle: The part of a flower stalk where the parts of the flower are attached. Sepal: The outer parts of the flower (often green and leaf-like) that enclose a developing bud.

Petal: The parts of a flower that are often conspicuously colored.


Flower Part




brightly coloured

attract insects


male part of the flower
made up of anther and filament




produces male gametes - pollen



supports anther to make it accessible to insects


male gamete - contains half the genetic information for the production of a new plant



contains ovules

After fetilisation, the ovary swells to produce fruit


the female reproductive part

produces the female gamete - egg


female parts of the flower, consisting of the stigma, style and ovary



sticky portion at the top of the style where pollen grains usually land



the narrow elongated part of the pistil between the ovary and the stigma

grows pollen tube


external covering of flower bud




supports flower

Meiosis is the process of cell division that produces gametes in the ovary and anther
Complete metamorphosis Animals whose bodies change dramatically during their life cycles go through complete metamorphosis. Example: egg, larva, pupa, adult. Insects that undergo complete metamorphosis: most insects, including moths, butterflies, beetles, wasps, flies, ants, and bees.
Direct Development A kind of growth where organisms keep the same body features as they grow larger
Egg the first stage in the life cycle of many organisms
Incomplete metamorphosis Some animals do not go through the full cycle of metamorphosis and only go through three stages of development: egg, nymph, adult.
Insects that undergo incomplete metamorphosis: mantises, walking sticks, roaches, aphids, damselflies, grasshoppers, katydids, water bugs, and others
Larva the small, wormlike stage in the life cycle of some insects
Life cycle the stages of growth and development that an organism goes through in its lifetime
Metamorphosis the changes in form that some insects go through during their life cycle
Molt to shed skin, scales, feathers, or an exoskeleton, usually at a particular time of year or stage of growth and development
Nymph looks like the adult. The second stage of life for insects that experience incomplete metamorphosis
Pupa the stage in the life cycle of some insects when the organism changes from a larva to an adult. An insect inside an enclosure, such as a chrysalis, transforming into an adult.
Incomplete Metamorphosis Incomplete: 
Praying Mantis
Dragon fly
Water bug
Complete Metamorphosis Complete:
Lady bug 
Complete metamorphosis- Metamorphosis through which the insect develops by four distinct stages: egg, larva, pupa, adult. A type of metamorphosis in which an organism's transformation is so dramatic that it is difficult to recognize the relationship between the larva and adult form.
Incomplete metamorphosis- where the young develop gradually, appearing similar to the adults and do not undergo a pupa stage. A type of metamorphosis that includes three stages—the egg, the nymph, and the adult
Metamorphosis a change in the shape or characteristics of an organisms' body as it grows
complete metamorphosis
complete metamorphosis
Vector Borne Diseases  

Serious diseases in human populations are carried by vectors - organisms that transmit pathogens and parasites from one infected person (or animal) to another.

Most commonly found in tropical and sub-tropical regions where access to safe drinking-water and sanitation systems are absent or lacking, these infectious diseases are a global burden. The most deadly vector-borne disease is malaria, however, dengue is the world's fastest growing vector-borne disease.

Mosquitoes can carry many viral diseases, such as dengue fever, West Nile virus and Yellow fever.

Dengue is transmitted mainly by Aedes species in the tropics.

Chikungunya is a viral disease that is also spread by mosquitoes which also transmit dengue virus.

Climate change, international trade and travel influence the distribution of vector-borne diseases.

When outdoors in mosquito-infested areas avoid mosquito bites by dressing properly and/or using insect repellents; wear long pants, shoes, socks and long sleeves, and apply insect repellents to exposed areas of skin.

Home doors and windows should be screened to prevent entry of mosquitoes. Elimination of larval habitats around your home and on neighboring properties is the most effective way to reduce the number of mosquitoes around a home. Remove or routinely dump water-containing items such as buckets or bird baths. Communities or health authorities may establish mosquito surveillance and control programs to reduce mosquito populations by spraying insecticides, treating drains and puddles with larvicides, and draining stagnant water from ditches.

complete metamorphosis

House flies are carriers of easily communicable diseases. House flies carry diseases on their legs and the small hairs that cover their bodies as they collect pathogens on their legs and mouths when females lay eggs on decomposing organic matter such as feces, garbage and rotting corpses.These pathogens are transferred to food or surface on which they land. Mature house flies also use saliva to liquefy solid food before feeding on it and transfer pathogens.

Diseases carried by house flies include typhoid, cholera and dysentery. Other diseases carried by house flies may include salmonella, anthrax and tuberculosis. House flies have also been known to transmit the eggs of parasitic worms.

Food for human consumption must be stored or displayed in such a way as to prevent flies from touching it. The numbers of houseflies should be kept as low as possible by removing decaying organic detritus in which they breed.

complete metamorphosis

Viral infectious disease is transmitted through the saliva and urine of rats. Bubonic plague, also called “Black Plague,” is a historically dangerous rat-borne disease. Transfer occurs when fleas, transported on rats, bite human beings. During the Middle Ages it which killed millions. Rat infestations are harmful to human health and also typhus and hantavirus. Rat droppings, dander and hair can cause people to sneeze and experience other allergic reactions.

Diseases transmitted by rats can be from direct exposure to rat-infected feces, urine or bites and indirectly transmitted to people by an intermediate vector such as fleas, ticks or mites.

complete metamorphosis

Human Stages of Growth

  1. Infancy -
    • birth to 18 months
    • bones are soft and flexible
    • Fast mental and physical development
  2. Early Childhood -
    • 18 months - 3 years
    • Arms and legs get longer
  3. Late Childhood
    • 6 to 12 years
    • begin to loose milk teeth
    • Sexual maturity begins
    • Higher level thinking skills acquired
  4. Adolescence
    • 12 - 18 years
    • Rapid physical growth
    • Body begins to take on adult look
  5. Adulthood
    • > 18 years
    • As age increases senses weakewn, bones loose calcium and joints and muscles weaken


Stage Time Growth
Gestation 40 weeks before birth Very fast
Infancy Birth to 2 years Fast
Childhood 3-10 years Steady growth and mental development
Adolescence 11-17 years Growth spurt, puberty, mental development
Adulthood 18-60 years Peak health and fitness but no increase in height
Old age 60 years to death Some tissue degeneration
human growth
Concept by Kishore Lal. Programmed by Kishore Lal... Copyright © 2015 Kishore Lal. All rights reserved.