1. Unit 3: Life Science

2. Life Science
Everything in the world around you can be grouped into two categories: living and nonliving things.
Living things include examples such as earthworms, bacteria, clams, and pine trees.
Nonliving things include examples such as water, air, and rocks.
The study of living and nonliving parts of the world is called ecology.

3. Ecology

4. What is Life Science?
The study of living things is called life science.
Another word for life science is biology.
Scientists who study living things are called biologists.
Biologists focus on a particular field of study.

5. Biology

6. Section 1: Living Things are Alike
Chapter 18
Section 1: Living Things are Alike

7. Living Things are Alike
All living things are made up of the same basic unit of life: the cell.
A cell is the basic unit of life.
It is the smallest thing that can be called “alive.”
Living things are made up of thousands, millions, billions, and even trillions of cells.
They make up blood, bone, skin, nerves, and muscle.
In plants they make up roots, stems, leaves, and flowers.

8. Cells

9. Living Things are Made up of Cells
Cells carry many functions, or jobs.
Some cells have specialized jobs:
Skin Cells: cover and protect
Muscle Cells: allow for movement
Bone Cells: support and protect
Blood Cells: transport materials and fight disease

10. Cells

11. Living Things are Made up of Cells
Another word for living things is an organism.
An organism is a complete, individual living thing.
It can carry out all basic life activities.
Living things may be as large as an elephant or as small as the bacteria that causes a sore throat.
Bacteria are the simplest living organisms.

12. Observing Cells Cells come in different sizes.
Most cells are so small that they are invisible to the unaided eye.
They can be seen only with a microscope.
A microscope is an instrument that scientists use to magnify small things in order to make them appear larger.

13. Observing Cells
A cell is surrounded by a thin membrane that encloses its contents.
Inside the cell are tiny structures called organelles.
They perform specific functions such as storing material or producing energy.

14. Cell Organelles

15. Tissues
Groups of cells that are alike and act together to do a certain job are called tissues.
Examples in animals include: muscle tissue, nerve tissue, bone tissue, and skin tissue.
Examples in plants include: root tissue, stem tissue, and leaf tissue.

16. Cell Tissue

17. Organs An organ is a group of different tissues that work together.
Organs are the main working parts of animals and plants.
They do a specific job:
The human heart—pumps blood through your body.
Lungs—allow you breathe.

18. Human Organs

19. Organs Main Organs in plants are roots, leaves, and stems.
Roots take in water from the soil.
Leaves make food for the plant.
Stems support the plant and carry water and food to different parts of the plant.

20. Plant Organs

21. Comparing Plant and Animal Cells
Plants and animals have different kinds of cells.
Similarities:
Both animal and plant cells have cell membranes that enclose the cell.
Both animal and plant cells are filled with cytoplasm, a gel-like substance containing chemicals needed by the cell.
Both animal and plant cells have a nucleus, where DNA is stored. DNA controls many of the characteristics of living things. Inside the nucleus is the nucleolus.
Both animal and plant cells have ribosomes, protein builders of the cell.

22. Comparing Plant and Animal Cells
Similarities (continued):
Both animal and plant cells have ribosomes, protein builders of the cell.
Both animal and plant cells have mitochondria that use oxygen to break down food and release the energy in food’s chemical bonds.
Both kinds of cells have vacuoles that contain food, water, or waste products. Animal cells usually have more vacuoles than plant cells do.
The cells of both plant and animals have endoplasmic reticulum, where a system of tubes process and transport proteins within cells.
The Golgi bodies in both plant and animal cells package proteins for distribution outside the cell.

23. Comparing Plant and Animal Cells
Differences:
Plant cells have cell walls that provide structure, but animal cells do not.
A few large animal cells have more than one nucleus, but plant cells always have just one.
Plant cells have chloroplasts for photosynthesis. Animal cells do not.
Animal cells tend to have small vacuoles. Mature plant cells may have only one large vacuole.
Animal cells have lysosomes, but plant cells do not.

24. Comparing Plant and Animal Cells

25. Cells Store and Use Energy
The energy that cells need comes originally from the sun.
Chloroplasts in plant cells trap light energy from the sun and change it into chemical energy.
This chemical energy is stored in chemical bonds between atoms of carbon, hydrogen, and oxygen.
An atom is the smallest particle of an element that still has the properties of that element.
Chemical bonds hold atoms together to form molecules.
A molecule is two or more atoms joined together.

26. Cells Store and Use Energy
Both plants and animals cells break down these molecules by breaking their chemical bonds.
Energy is stored in these bonds.
Energy is released when the bonds are broken.
Cells can either use the energy or store it.

27. Cells Store and Use Energy
The mitochondria in plant and animal cells use oxygen to release the energy in chemical bonds.
Cells store the chemical energy from food in high-energy ATP molecules.
ATP stores energy in a form the cells can easily use.
When a cell needs energy, the ATP is broken down to release energy.

28. Cells Store and Use Information
The nucleus of the plant and animal cells is the control center of the cell.
The nucleus contains DNA, a molecule that has instructions for all of a cell’s activities.
One of these activities is putting together protein molecules.
Cells require thousands of proteins in order to work well.
DNA and RNA molecules work together in the cell to make the proteins.

29. Cells Store and Use Information
DNA in the cell’s nucleus determines what kind of cell it is.
When a cell divides and becomes two cells, the information needs to be passed on.
To make certain that each cell has the same information, the DNA doubles when the cell divides.
Each of the two new cells contains the needed information to carry out all the cell’s activities.

30. Nucleus

31. Section 2: Chemicals that are Important for Life
Chapter 18
Section 2: Chemicals
that are Important for Life

32. Chemicals that are Important for Life
Living things use chemicals to stay alive.
Water is one of the chemicals that all living things use.
Life cannot exist without water.
Water is found in each of the 100 trillion cells in the adult human body.
It makes up about 2/3 of the weight of the cell.

33. Importance of Water Water is a useful chemical.
Example: sugar being dissolved in coffee or tea.
The ability to dissolve chemicals is one of the most important properties of water.

34. Carbohydrates Carbohydrates are sugars and starches.
Sugar is used to sweeten many foods and is found naturally in many fruits and vegetables.
Starches are found in foods such as bread, cereal, pasta, rice, and potatoes.
Plants use the energy from sunlight make carbohydrates from carbon dioxide and water.
The gas carbon dioxide is found in the air.
Animals get energy from the carbohydrates that plants make.

35. Carbohydrates

36. Carbohydrates Energy is needed to carry on various life activities.
Carbohydrates in your body act like gasoline in a car.
When carbohydrates are broken down inside your body energy is released.
This energy powers your body.

37. Fats Fats can also be thought of as fuel chemicals.
Fats store large amounts of energy that are released when they are broken down.
Of all the chemicals important for life, fats contain the most energy.
They are found in foods such as meat, butter, cheese, and peanut butter.
Fats are solid at room temperature.

38. Fats

39. Proteins
Like carbohydrates and fats, proteins provide energy for living things.
Meats such as beef, chicken, and fish contains large amounts of proteins.
Beans, nuts, eggs, and cheese also contain large amounts of protein.
Proteins also help to repair damaged cells and build new ones.
Hair, muscle, and skin are made mostly of proteins.
Proteins also help control body activities such as heart rate and the breaking down of fat in the body.

40. Proteins
Proteins are made up of long chains of smaller molecules called amino acids.
There are 20 different amino acids that can be arranged in different ways to make different proteins.
There are many different kinds (combinations) of proteins and they perform a variety of jobs.
These jobs include digesting food, fighting infections, controlling body chemistry, and keeping the body working smoothly.

41. Amino Acids

42. Proteins
The DNA in a cell nucleus contains the code that’s needed to produce a protein.
When a cell receives a signal that a certain protein is needed, the DNA inside the nucleus reproduces the code.
The code is then carried by the RNA out into the cell.
Ribosomes read the DNA.
The Ribosomes join together the chains of amino acids using the RNA codes to produce the needed protein.

43. Importance of Nutrients
To keep your body working properly you need a regular resupply of carbohydrates, proteins, and fats from the foods you eat.
It is important to eat a variety of foods because each different kind of food provides a different protein that your body needs.
Your body also needs vitamins and minerals.
Minerals are natural substances that your body needs to work properly.
Vitamins are used by your body for growth and activity.
Your body needs these in small amounts only.
The chemicals that are needed for life and that come from foods are called nutrients.
To be healthy, living things need to take in the right amount of nutrients every day.

44. Section 3: Basic Life Activities
Chapter 18
Section 3: Basic Life Activities

45. Getting Food Animals get food by eating plants or other animals.
Plants make their own food.
They use the energy from sunlight to make carbohydrates from carbon dioxide and water.

46. Using Food and Removing Waste
Digestion is a life activity that breaks down food into chemicals that cells can use.
Respiration is when cells release the stored energy, but this process also produces waste.
Excretion is the process that removes waste from living things.

47. Movement Movement is another activity that is common to living things.
Plants do not move from one place to another, but they still move.
Plants have roots that hold them in place, but their parts bend and move.
Besides outward movement, there is constant movement inside living things.
Liquids are flowing, food is being digested, and materials are moving in and out of cells.

48. Sensing and Responding
Living things sense and respond.
Animals and plants have tissues and organs that pick up, or sense, signals from their surroundings.
These signals include light, sound, chemicals, and touch.
Plants and animals change something, or respond, based on the kinds of signals they pick up.

49. Homeostasis
Organisms have the ability to maintain their internal conditions.
This ability is called homeostasis.
Example: your bodies ability to keep your temperature within a normal range.

50. Growth Growth is part of being alive. Example: baby to adult.
You will continue to grow until you reach your adult size.
Most living things go through a similar pattern of growth.

51. Growth

52. Reproduction Living things produce offspring.
Some living things reproduce by themselves.
Example: bacteria dividing itself in two.
For other living things, such as humans, reproduction involves two parents.
The offspring of all living things resembles their parent or parents.

53. Development
Many living things develop as they grow.
Development means becoming different, or changing, over time.
Examples: Frogs and Butterflies.

54. Development

55. Section 4: How Organisms are Classified
Chapter 18
Section 4: How Organisms
are Classified

56. How Organisms are Classified
All living things carry out the same basic life activities but they can still be very different from one another.
Scientists divide the world of living things into five groups, or kingdoms.
Plant
Animal
Protists
Fungi
Monera

57. 5 Kingdoms

58. How Organisms are Classified
Biological Classifications, or groupings, are based on how organisms are related.
The study of living things is called biology.
The science of classifying organisms based on the features they share is called taxonomy.

59. The Plant Kingdom Most plants are easy to recognize.
Plants don’t move from place to place like animals.
They don’t need to do so.
Plants make their own food, using sunlight and other substances around them.
All plants have many cells.
These cells are organized into tissues.
Many plants also have organs.

60. Plant Kingdom

61. The Animal Kingdom Animals have many different sizes and shapes.
Animals cannot make their own food.
They get their food from other living things.
They eat plants, or they eat other animals that eat plants.
Most animals move around to capture or gather their food.
Moving also helps them to find shelter, escape danger, and find mates.
All animals have many cells.
These cells form tissues in all animals except the sponge.
In most animals, the tissues form organs.

62. Animal Kingdom

63. The Protist Kingdom
Until the microscope was invented only the plant and animal existed.
When scientists used the microscope they discovered tiny organisms.
They called them microorganisms because they could only be seen under a microscope.
These organisms did not fit into the plant or animal kingdoms.
Biologists placed them into a separate kingdom which they called protists.

64. The Protist Kingdom Most protists have only one cell.
A few have many cells.
Some protists make their own food.
Others absorb food from other sources.
Algae are plantlike protists.
Protozoans are animal like protists.
Some protozoans have properties of plants and animals.
All protists carry out the basic life activities.

65. Protist Kingdom

66. The Protist Kingdom
Algae live in lakes, streams, rivers, ponds, and oceans.
Algae grows as green scum on ponds.
The green scum is thousands of tiny algae.
Like plants, algae can make their own food.
Algae are food for the organisms that live in the water.
Many larger algae are called seaweeds.
Some seaweeds can become as large as a football field.
Algae also produce oxygen that other organisms use.

67. Algae

68. The Protist Kingdom
Protozoans live in water, soil, and the bodies of animals.
Most protozoans are harmless.
Some cause disease.
Protozoans behave like animals by getting food and moving.
Different kinds of Protozoans have different methods of moving.
Flagella—a whiplike tail
Cilia—hairlike strictures
Pseudopods—part that sticks out like a foot

69. The Protist Kingdom
Euglenas are protozoans that behave like both plants and animals.
Like plants, they make their own food when sunlight is present.
Like animals, they can absorb food from their environment which they do when sunlight is not present.

70. Euglenas

71. The Fungi Kingdom Most fungi have many cells.
Like plants, fungi do not move around by themselves.
But unlike plants, fungi do not make their own food.
They absorb food from other organisms.

72. The Fungi Kingdom
Because of the way fungi get food, they are important to other organisms.
Fungi release special chemicals on dead plant and animal matter.
The fungi then absorb the decomposed material.
Some of the decomposed material also gets into the soil.
Other organisms, such as plants, use this material.

73. The Fungi Kingdom Some fungi are parasites.
They absorb food from a living organism.
Some fungi hurt plants (Dutch elm).
Some fungi harm animals (ringworm).

74. Fungi Kingdom

75. The Monera Kingdom Monera means “alone.”
This kingdom has only one kind of organism, bacteria.
Monerans are usually one-celled organisms.
Like animals, some can move and get food.
Like plants, some stay put and make their own food.
Bacteria cells are different from the cells of all other organisms because bacteria do not have organelles in their cells.
Organelles are tiny structures in cells that do certain jobs.

76. The Monera Kingdom Some bacteria cause disease (strep throat).
Most bacteria are harmless.
Many are even helpful.
Like fungi, bacteria help to decompose the remains of plants and animals.
People also use bacteria to make foods such as cheese and yogurt.

77. Monera Kingdom