Unit 1 Introduction to biology
Key unit competence: Apply the concepts of biology, safety rules and first aid in daily life.
Key ideas
- Biology comes from two Greek words: "bios" (life) and "logos" (study). Biology is the study of living organisms: how they are built, how they work, how they interact with each other and with their environment.
- An organism is any living thing. Organisms range from microscopic unicellular organisms such as bacteria to huge multicellular organisms such as eucalyptus trees, whales and elephants.
- Main branches: botany (plants), zoology (animals), microbiology (microorganisms), ecology (interactions between organisms and their environment), taxonomy (classification), cytology (cells), anatomy (structure), physiology (how parts work), genetics (inheritance), biochemistry (chemical reactions in cells), biotechnology (using organisms to solve problems), entomology (insects), parasitology (parasites).
- Biology is important socially (health, hygiene, disease prevention), economically (agriculture, livestock, fish farming, beekeeping, ecotourism, medicines) and for the environment (conservation, pollution control). It also opens careers: doctor, nurse, veterinarian, laboratory technician, agronomist, teacher, forensic scientist.
- The seven characteristics of living things can be remembered as MRS NERG: Movement, Respiration, Sensitivity, Nutrition, Excretion, Reproduction, Growth. An organism is alive only if it shows all of them during its life.
- Movement is a change of position of part or all of an organism; locomotion is movement of the whole organism from place to place (animals). Plants move parts, for example leaves turning towards light. Growth is a permanent (irreversible) increase in size; development is the change in form and function towards maturity.
- Respiration releases energy from food in every living cell. Excretion removes waste made by the body (carbon dioxide, urea). Removing undigested food (egestion) is not excretion.
- Laboratory safety: follow the teacher's instructions; never work without the teacher; never taste, eat or drink in the laboratory; point a heated test tube away from people; never return chemicals to the stock bottle; report spills, breakages and injuries at once; wash hands after practical work; dispose of waste in the right container; know where the fire extinguisher and first aid kit are.
- First aid is the immediate help given to an injured person before medical help arrives. A first aid kit contains, for example, sterile bandages, plasters, cotton wool, antiseptic, gloves, scissors, eye-wash and pain relief.
- First aid for common laboratory injuries: heat burn: cool under running water, cover with a clean non-stick dressing; chemical burn: flood with cool water for at least 20 minutes, never try to neutralise it with another chemical; cut: press on the wound to stop bleeding, clean, cover; chemical in the eye: flush with clean water for about 15 minutes, then go to a clinic.
Common misconceptions
- "Excretion and egestion are the same." No: excretion removes waste made by body cells (CO₂, urea); egestion removes undigested food that was never part of the cells.
- "Plants are not living because they do not move." No: plants move parts of their bodies (leaves, stems, roots) slowly in response to light, gravity and touch; they just do not show locomotion.
- "A car is living: it moves, uses fuel and gives out exhaust gases." No: a car cannot grow, reproduce or respond to stimuli by itself, so it does not show all the characteristics of life.
- "On a chemical burn, add another chemical to cancel it." No: neutralising can make heat and worsen the burn; flood it with plenty of cool water.
Worked examples
Example 1. A learner finds a seed in a dry bag. It does not move or feed. Is it living or non-living? Explain.
Solution
A dry seed shows very slow respiration and no visible growth, but it is alive: when planted with water, warmth and air, it germinates, grows, feeds, and later reproduces. Living things show all seven characteristics during their life, not necessarily at every moment.
Example 2. During a practical, a learner spills dilute acid on her hand. Describe the first aid she should receive.
Solution
Remove contaminated clothing, flood the skin with cool running water for at least 20 minutes, do not apply another chemical, cover with a dry sterile dressing, report to the teacher and go to a clinic if the skin is damaged.
Practice questions
Define biology and name four of its branches, saying what each studies.
Show answer
Biology is the study of living organisms. Botany (plants), zoology (animals), ecology (interactions of organisms with their environment), genetics (inheritance). Others: microbiology, taxonomy, cytology, anatomy, physiology.
Common mistake: Giving the branch names without saying what each one studies.
State the seven characteristics of living things.
Show answer
Movement, respiration, sensitivity, nutrition, excretion, reproduction, growth (MRS NERG).
Common mistake: Writing "breathing" instead of respiration.
Distinguish between movement and locomotion, with one example of each.
Show answer
Movement is a change of position of part or all of an organism, for example a leaf turning towards light. Locomotion is movement of the whole organism from one place to another, for example a goat walking.
Common mistake: Saying that plants show locomotion.
Give three reasons why the study of biology is important in Rwanda.
Show answer
It helps prevent and treat diseases (malaria, HIV); it improves farming and livestock production; it protects the environment and wildlife (national parks, ecotourism). It also opens careers in health and agriculture.
Common mistake: Giving vague answers such as "it is good" without an example.
List four laboratory safety rules and give the reason for each.
Show answer
Do not eat or drink (food may be contaminated); point heated test tubes away from people (liquid can spurt out); report spills and breakages (others can be hurt); wash hands after practical work (removes chemicals and microorganisms).
Common mistake: Listing rules without the reasons.
Describe the first aid for a chemical burn on the arm.
Show answer
Wear gloves, remove contaminated clothing, flood the burn with cool running water for at least 20 minutes, do not add another chemical, cover with a dry sterile dressing and go to a clinic.
Common mistake: Trying to neutralise the chemical with another chemical.
Explain why a stone is non-living even though it may "grow" bigger as material sticks to it.
Show answer
The stone gets bigger only by material added to its outside; it does not feed, respire, respond, excrete or reproduce, and it is not made of cells.
Common mistake: Thinking that any increase in size is growth.
Name four items found in a first aid kit and state the use of each.
Show answer
Sterile bandage (covers wounds), antiseptic (kills germs on a wound), gloves (protect the first aider from blood and chemicals), scissors (cut bandages or clothing), eye-wash (rinses the eye).
Common mistake: Naming laboratory apparatus instead of first aid items.
Matching and drag-and-drop
Matching
Match each item in column A with the correct answer in column B. Write the letter next to each number.
Column A Column B 1. Plants obtain their food by: a. making it by photosynthesis using light energy 2. Which branch studies the interactions between organisms and their environment? b. Ecology 3. Which process releases energy from food in all living cells? c. cool it under cool running water 4. The first thing to do for a heat burn is to: d. Respiration Show answer
1 → a (making it by photosynthesis using light energy) · 2 → b (Ecology) · 3 → d (Respiration) · 4 → c (cool it under cool running water)
- Green plants make their own food from carbon dioxide and water using sunlight.
- Ecology studies how organisms depend on each other and on their surroundings.
- Respiration is a chemical process in cells; breathing only moves air in and out.
- Cooling reduces pain and stops the burn from going deeper.
Drag and drop
Choose the correct word or phrase from the box for each gap. One word in the box is not needed.
the characteristics of living things · sensitivity (irritability) · the study of life · nutrition (feeding)- The mnemonic MRS NERG helps to remember .
- The word "biology" means .
- The ability of an organism to detect and respond to changes around it is .
Show answer
1: the characteristics of living things · 2: the study of life · 3: sensitivity (irritability)
- Movement, Respiration, Sensitivity, Nutrition, Excretion, Reproduction, Growth.
- From Greek: bios = life, logos = study.
- Sensitivity lets organisms find food and escape danger.
Matching
Match each item in column A with the correct answer in column B. Write the letter next to each number.
Column A Column B 1. The study of how parts of an organism work is: a. botany 2. The study of the transfer of characters from parents to offspring is: b. physiology 3. The branch of biology that studies plants is: c. locomotion 4. Movement of a whole organism from one place to another is called: d. genetics Show answer
1 → b (physiology) · 2 → d (genetics) · 3 → a (botany) · 4 → c (locomotion)
- Anatomy studies structure; physiology studies function.
- Genetics is the study of inheritance.
- Botany is the study of plants; zoology is the study of animals.
- Animals show locomotion; plants move only parts of their bodies.
Drag and drop
Choose the correct word or phrase from the box for each gap. One word in the box is not needed.
taxonomy · excretion · anatomy · entomology- The removal of waste products made by the body's cells is called .
- The branch of biology that studies insects is .
- Classifying organisms into groups according to their similarities is called .
Show answer
1: excretion · 2: entomology · 3: taxonomy
- Excretion removes metabolic wastes such as carbon dioxide and urea.
- Entomology studies insects and how they affect humans.
- Taxonomy is the science of classification.