Science Biology Unit Test - Grade 10

Cells and Cell Theory - Three Main Ideas

1. All living organisms are made of one or more cells.

2. The cell is the basic organizational unit of life.

3. All cells come from pre-existing cells.

Cells and Cell Theory - Charactistics of Living Things

• Need and use energy

• Reproduce offspring like themselves

• Grow

• Are made of cells

• Produce waste

Cells and Cell Theory - What is an Organelle and What Does it do?

Organelle: A part or structure within a cell that carries out specific functions to support the life of the cell.

Organelle Functions:

• Bringing in nutrients, removing wastes

• Generating energy for the cell

• Making substances that the cell needs

• Reproducing

Cell and Cell Theory - Nucleus

This organelle is the easiest to see in plant and animal cells.

Controls the cell’s activities (the “brain” of the cell)

It contains the cell’s DNA (instructions on how to make more cells)

Cell and Cell Theory - Cell Membrane

A semi-permeable barrier (only lets certain things in and out)

Controls what goes in and out of the cell (like security)

It protects the cell, and maintains its structure

Cell and Cell Theory - Cell Wall

A thick wall around the cell membrane

Provides extra support to the cell

Allows the cell to fill with more liquid without bursting

Cells and Cell Theory - Mitochondria

Battery-shaped

Sometimes called the “powerhouse of the cell”

Provides the cell with energy (like a battery)

Cells and Cell Theory - Chloroplasts

Converts sunlight into food for plants (photosynthesis)

Cells and Cell Theory - Endoplasmic Reticulum

Always connected to nucleus

Network of channels that transport materials made in the cell (like a conveyor belt)

Cells and Cell Theory - Ribosomes

Make proteins for the cell to use

They follow the DNA instructions to make new structures and even new cells

Cells and Cell Theory - Golgi Body

Looks like a stack of curved pancakes

Sorts and packages materials (like chemicals/nutrients) into membranes called “vesicles”

Vesicles can be sent to other cells

Cells and Cell Theory - Vesicles

Sacs that transport and/or store materials inside the cell or to other cells

Cells and Cell Theory - Vacuole

A “water balloon” that contains water & nutrients

Plant cells - 1 large vacuole

Animal cells - many small vacuoles

Cells and Cells Theory - Cytoplasm

Jelly-like substance, composed mainly of water & sugar

Holds/supports all of the organelles

Cells and Cell Theory - Cytoskeleton

Filaments/tubules (small fibres) - helps the cell keep its structure

Provides “tracks” along which vesicles and organelles can move

Cells and Cell Theory - Lysosomes

Small sacs that contain digestive chemicals that break down materials

Cell Division - Reasons for cell division

1. Heal

2. Growth

3. Maintenance

Cell Division - DNA

Carries all of the genetic information of a cell and is found in the nucleus.

Cell Division - Chromosomes

Chromosomes are long pieces of coiled DNA and proteins

Cell Division - Interphase

During interphase the cell:

- Grows

- Makes a copy of its DNA

- Prepares for cell division

During interphase, chromosomes are not visible because the DNA is spread out in the form of Chromatin.

The cells spends 90% of its time in interphase. Interphase is split up into 3 phases:

(i) G1

(ii) S

(iii) G2

Cell Division - 3 Stages of Interphase

G1 Phase: Growth Phase 1

- The cell grows in size, produces new proteins and organelles

S Phase: Synthesis

- The cell makes a copy of its DNA

G2 Phase: Growth Phase 2

- The cell produces structures and organelles needed for cell division

- Shortest stage of interphase

Cell Division - Mitosis

Process where: replicated chromosomes are separated into two nuclei

Cell Division - Step one Mitosis

Prophase: the chromatic condenses into visible chromosomes. The centrioles start moving to the ends of the cell. Spindle fibres are made by centrioles. Nucleus is broken down so that the chromosomes are few to move around the cell. Each chromosomes is connected to a spindle fibre. This allows them to be moved.

Cell Division - Step two Mitosis

Metaphase: The chromosomes are lined up at the middle of the cell

Cell Division - Step three Mitosis

Anaphase: The chromosomes are split and one copy of each starts moving to either end of the cell.

Cell Division - Step four Mitosis

Telophase: two new nuclei are made. The chromosomes unwind into chromatin.

Cell Division - Cytokinesis

Cytokinesis begins during telophase. The cell membrane pinches the cytoplasm in half to make two new daughter cells.

Cell Division - Cancer

The disease caused by an uncontrolled division of abnormal cells in a part of the body

Specialized Cells: Stem Cells

Stem cells can turn into any other type of cell.

These are mostly found in embryos.

Stem cells are undifferentiated cells with the potential to either continuously divide or become a variety of different cell types.

Specialized Cells: Differentiation

A stem cell becomes specialized in a process called differentiation

Once a stem cell has specialized, it cannot go back

Specialized Cells: Uses for Stem Cells

Stem cells can be used to treat diseases and to replace damaged tissues

Scientists are researching the use of stem cells to solve many medical problems

Specialized Cells: Types of Stem Cells

Embryonic stem cells

Adult stem cells

Specialized Cells: Embryonic Stem Cells

Found in embryos

Can undergo differentiation to become any type of human cell (there are over 200!).

Specialized Cells: Finding Embryonic Stem Cell

Sexual reproduction begins when a sperm fertilizes an egg forming a ‘zygote’ or ‘first whole cell’.

The zygote will undergo the cell cycle again and again forming a cell mass termed a ‘morula’

The morula cells divide and a blastocyst is formed which consists of an inner cell mass and an outer cell mass.

The outer cell mass (trophoblast) becomes part of the placenta. The inner cell mass is a collection of stem cells.

Specialized Cells: Adult Stem Cells

We need a supply of cells to replenish cells in our body as we grow and age.

Adult stem cells are found in different regions of the body and develop into specialized cells and tissue to support growth and repair of our tissues and organs.

Can specialize to become a limited number of cell types.

Specialize to become cells from their tissue of origin.

E.g. Blood-forming stem cells can become red or white blood cells.

Also called multipotent or tissue stem cells

Specialized Cells: What are Specialized Cells

Specialized Cells - specialized to do 1 specific job

Specialized Cells: Why do cells specialize

Unicellular Organisms - a single-cell organism that performs ALL required functions within the cell (e.g., amoeba)

Multicellular Organisms - much more complex and are made of many cells

The body needs to:

Supply food and nutrients

Transport materials

Remove waste

Fight infection

Different cells are needed to perform all of these specific functions!

Specialized Cells: Red Blood Cells

Location: Blood

Function: Carry oxygen

Specialized Design:

Large surface area (for oxygen to pass through)

Has NO nucleus

Contains hemoglobin which binds with oxygen

Specialized Cells: Sperm Cells

Location: Testes

Function: Fertilize eggs

Specialized Design:

Small and move easily

Long tail allows for movement (needs to swim)

The head contains enzymes, which allow the sperm to digest into an egg

Specialized Cells: Egg Cell

Location: Ovaries

Function: Be fertilized

Specialized Design:

Large and bulky

Contains a ‘yolk’ as a food source

No active movement

Specialized Cells: Nerve Cell

Location: All over the body

Function: Carry nerve signals to/from brain

Specialized Design:

Long with connections at each end

Can carry electrical signals

Specialized Cell: Muscle Cell

Location: All over the body

Function: Body movement

Specialized Design:

A muscle can change length

Some are long and react quickly (skeletal)

Some never get tired (cardiac)

Some work automatically (smooth)

Tissues: Types of Tissues

There are 4 major types of tissues in the body, all made up of similar cells working together.

Epithelial tissue

Muscular tissue

Nervous Tissue

Connective Tissue

Tissues: Epithelial Tissue

Skin Tissue

Forms a barrier by connecting cell membranes

On the inside & outside surfaces of the body

Fast growth/renewal rate

Tissues: Muscular Tissue

Designed to change their shape

Move the body or organ by contracting & relaxing

Tissue: Connective Tissue

Strengthens, supports & protects other tissues

Connective tissue can be in:

Solid (bone)

Liquid (blood)

Elastic (ligaments)ens, supports & protects other tissues

Tissue: Nervous Tissue

Made of neurons that send & receive signals

Coordinates body actions & functions

Immunization Myths

• Vaccines cause autism

• Vaccines contain toxic ingredients

• Natural is better. We shouldn’t put foreign substances like vaccines into our bodies

How Many Chromosomes Do Humans Have?

23 pairs (46 individual chromosomes)

The BIG QUESTION

While doing a physical activity like running you use many organ systems. One organ system that you use is the muscular system. You mostly use the core muscles and lower body muscles while running. An organ that’s in the muscular system is the skeletal muscle. The skeletal muscle is attached to bones (skeletal system) and helps move them. There is a lot of connective tissue in skeletal muscle. One type of connective tissue is endomysium tissue. This tissue helps organize and support individual muscle fibres. Endomysium tissue allows muscle fibres to easily slide past each other while contracting. It also plays a big role in protecting and strengthening the muscle fibres. This tissue contains many capillaries (circulatory system) that help supply blood to the muscle fibres. The capillaries also allow exchanges of nutrients, gases, and waste products. Another system that is  used while running is the skeletal system. Bones are really important organs found in the skeletal system. Connective tissue is commonly found in the skeletal system. Cartilage tissue is an important type of connective tissue that is used in this organ system. Cartilage helps cushion joints and provides support to help bones move smoothly. The cartilage helps reduce stress in bones during movement. Cartilage is smooth and low-friction. This creates a surface for bones to slide against each other. The circulatory system is another important system used while running. When you’re being physically active your body requires more oxygen. The circulatory system allows oxygen to be delivered to different parts of your body. Organs in the circulatory system include the heart and blood vessels. Connective tissues and muscle tissues are found in the circulatory system. Cardiac muscle tissue helps pump the heart. Connective tissue like blood exists inside blood vessels. Blood helps carry important nutrients throughout the body. The digestive system turns the nutrients in food into usable energy and it diffuses into blood when they are in the small intestine. The energy is then carried and distributed throughout the body in the circulatory system. This energy can help us while running. Blood also helps carry oxygen throughout the body. The respiratory system uses the lungs to exchange gases. The oxygen that is inhaled by the nose and sent to the lungs by the trachea diffuses into our bloodstream. A specialized cell in blood is the red blood cell. Red blood cells contain hemoglobin which help blood carry oxygen around. Red blood cells have a large surface area allowing them to carry a lot of oxygen. Also they don’t have a nucleus. This helps them carry more hemoglobins and proteins. The nervous system can also help us while running by helping us regulate our heart rate (circulatory system) and improving our focus.