Biology Midterm Study Guide Chapters 1-3.4
Dr. Laurie Solis
A, C period
Chapter 1-Life on earth
KEY CONCEPT
Biology is the study of all forms of life.
Earth is home to an incredible diversity of life.
• The biosphere includes all living things and all the places they are found.
• Every part of the biosphere is connected with every other part.
• The biosphere includes many environments.
• land environments
• The biosphere includes many environments.
• saltwater and freshwater environments
• Biodiversity is the variety of life.
• Biodiversity generally increases from the poles to the equator.
• Biodiversity is greater in areas with consistently warm temperatures.
• Biodiversity is greater closer to the equator.
A species is one particular type of living thing.
– Members of a species can interbreed to reproduce.
– There are about 2 million different living species have been identified.
All organisms share certain characteristics.
• Biology is the scientific study of all forms of life.
• An organism is any individual living thing.
• All are made of one or more cells.
• All need energy for metabolism.
• All respond to their environment.
• All have DNA that they pass on to offspring.
Chapter 2- Properties of Water
 Water gives cells structure
 Water transports vital materials to and from organs in the body
 All of the processes of life take place in the watery liquid in the body
 Water’s unique properties and cellular structure are important for living things.
 The ice acts as an insulator .
 Water expands when it freezes (That means it gets bigger)
 This is different from most liquids
Water is a polar molecule – because the hydrogen molecules are on opposite ends of the oxygen
molecule (H2O)
 Oxygen is the nucleus (8 protons)
 Hydrogen (1 proton)
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Oxygen has a stronger pull
Hydrogen gains small positive charges
The opposite charge of polar molecules interact to form hydrogen bonds
A hydrogen bond is an attraction between a slightly positive hydrogen atom and a slightly
negative atom, often oxygen or nitrogen.
Water has a hydrogen bond
Other liquids do too
Hydrogen bonds are part of the structures of proteins and of DNA.
Water has a strong bond in the molecule – this bond is the hydrogen bond
With out this bond, water would act differently…
Water would boil at a lower temperature
Water would freeze at a higher temperature
High Specific Heat: Water resists changes in temperature
Cohesion: Water sticks together (creates surface tension), such as when bugs land on water, or
water beads up on a newly washed car
Adhesion: Water sticks to things. Such as inside a test tube, a water bottle, or the way water
can be transported from the roots of plants to leaves.
Chapter 3 – Looking inside cells
 Key Concept: A cell wall is a stiff layer that helps to protect and support a plant cell.
 Animal cells do NOT have cell walls.
 Many materials like oxygen and water can pass through the cell wall.
 Key Concept: In the cytoplasm there are many organelles that have a specific function.
 Cytoplasm- gel-like fluid – What does it do?
 Key Concept: The cell membrane controls what substances go into and out of a cell.
 For a cell to live, the cell membrane must let material pass in and out of the cell.
 The cell wall is only found in the plant
 The cell membrane is found in the cell wall and the cell membrane
 Cell wall is like a wall of a house it is strong! The cell wall is made of
CELLULOSE….REMEMBER THAT!
 The cell membrane is like a screen: it allows some materials in and keeps others out.
 Key Concept: The nucleus is the control center of the cell and directs all of the cell’s activities.
 The nucleus is protected by a membrane called the nuclear envelope.
 The nucleus holds genetic information. Genetic information controls what the cell
does.
 The genetic information inside the nucleus is called DNA (deoxyribonucleic acid)
 The nuclear envelope has holes called pores that allows necessary molecules to pass
between the nucleus and the cytoplasm
 Endoplasmic Reticulum- Interconnected network of thin folded membranes that form a maze. It
aids in the important production of proteins and lipids (necessary fats)
 Ribosomes- protein factory
 Golgi apparatus- process, sort, and deliver the proteins to where they need to go.
 Vesicles – Isolate and transport molecules
 Vesicles are small sacks that divide materials from the rest of the cytoplasm and take things
from place to place
 Cells sometimes need to isolate (separate) different chemicals until they are ready to be
used
 Mitochondria- power house
 Vacuoles- Fluid filled sac used for storage by the cell.
 Plant cell: one large vacuole. Like a swimming pool
 Animal cell: many small ones like cupboards.
 Lysosomes- rids the cell of waste. (Like a garbage disposal.)
 Centrioles Cylinder shaped organelles made of short microtubules arranged in a circle
 Chloroplasts- capture sunlight for energy to make food. (only in PLANTS)
 Chloroplasts also have pigment (color)
 Only the chloroplasts that have chlorophyll can carry out photosynthesis
 The rate of photosynthesis increases as the number of chloroplasts with chlorophyll
increases
 That means: it happens faster
 Principles of Cell Theory are:
 1) All organisms are made of cells
 2) All existing cells are produced by other living cells
 3) The cell is the most basic unit of life
 Prokaryotic cells:
 do not have a nucleus or other membrane bound organelles.
 Instead the cell’s DNA is suspended in the cytoplasm.
 Most prokaryotes are microscopic single celled organisms
 Eukaryotic cells:
 Have a nucleus and other membrane bound organelles
 The nucleus (the largest organelle) encloses the genetic information
 Eukaryotes may be multi-cellular or single celled organisms
 This includes all animals and most plants
 KEY CONCEPT Materials move across membranes because of concentration differences.
 Passive transport does not require energy input from a cell.
 There are three types of solutions.
 Isotonic
 Hypertonic
 hypotonic
Other:
Review all of your labs. You will be asked questions about how this knowledge can be applied to your
activities. If you have not completed all the labs, check the HF website and do them at home.