biology 44 q's review sheet flashcards

What is biology?

The study of living things/life

What are the characteristics of living things?

Made of cells, reproduce, respond to stimuli, maintain homeostasis, evolve, heal, die and decay.

What is the correct order of the scientific method?

We make an observation, formulate a hypothesis, making predictions based on the hypothesis, and testing those predictions.

Approximately how old is Earth?

4.5 billion years.

How did organic compounds such as fats, sugars, and amino acids form on early Earth?

Organic compounds such as fats, sugars, and amino acids formed spontaneously from early atompsheric gases and energyearly atmospheric gases and energy.

The composition of the following polymers are true

Proteins are made of amino acids, complex carbohydrates are made of sugars, lipids are made of fatty acids and glycerol, and DNA is made of nucleotides.

How is genetic information passed from parents to offspring?

through molecules known as DNA.

What are true statements about lipids?

1. Triglycerides contain three fatty acid chains

2. lipids have nonpolar properties

3. double bonds create bends in fatty acid carbon chains, and unsaturated fats are more fluid.

4. When a protein is added to a fat to form a lipoprotein, the fat becomes more soluble in water because amino acid side chains can carry a charge.

What are the four levels of protein structure

1. Primary structure → sequence of amino acids.

2. Secondary structure → twisting and folding of amino acid chains.

3. Tertiary structure → three-dimensional shape of one folded chain.

4. Quaternary structure → two or more folded polypeptide chains together.

What stabilizes protein folding?

1. Hydrogen bonds

2. Disulfide bridges

3. Ionic bonds

4. Hydrophobic interactions

What are the properties of proteins?

1. Proteins can undergo denaturation when they lose their shape due to extreme pH or high temperatures.

2. Membrane-spanning regions of proteins are usually hydrophobic.

3. Proteins located on the surface of cell membranes usually contain hydrophilic regions.

4. Soluble proteins usually have a hydrophilic surface and a hydrophobic core.

What are the functions and properties of enzymes?

1. Enzymes increase the rate of a chemical reaction.

2. Enzymes decrease the activation energy of a reaction.

3. The active site of an enzyme binds to a single specific substrate.

4. If the product of an enzyme is part of multiple metabolic pathways, a drug that inhibits its production may have side effects.

What is the difference between dehydration synthesis and hydrolysis reactions?

1. Dehydration synthesis is a reaction that joins smaller molecules together to form a larger molecule by removing water.

2. Hydrolysis is a reaction that breaks a larger molecule into smaller molecules by adding water.

What is the correct order of size from smallest to largest?

1. electron (smallest)

2. proton

3. atom

4. molecule

5. virus particle

6. prokaryotic cell

7. eukaryotic cell (largest)

What occurs during DNA replication?

1. Helicase unwinds the DNA.

2. DNA polymerase adds nucleotides to the new strands.

3. Ligase joins the Okazaki fragments on the lagging strand.

4. DNA replication results in two DNA molecules, each containing one original strand and one newly replicated strand (semiconservative replication).

5. Occasionally, a mistake occurs (about 1 in 10 billion nucleotides), which can result in a mutation.

What happens during protein synthesis?

During protein synthesis, DNA is transcribed into RNA, and the RNA is then translated into a protein.

What occurs during transcription?

1. A ligand binds to the repressor protein, changing its shape and causing it to release from the promoter region of the gene.

2. RNA polymerase binds to the gene.

3. RNA polymerase transcribes the DNA strand to produce complementary messenger RNA (mRNA).

4. Transcription ends when RNA polymerase recognizes the stop sequence.

What is true about translation?

1. Ribosomal RNA (rRNA) binds to messenger RNA (mRNA).

2. Every three bases (a codon) on the mRNA code for one amino acid.

3. Transfer RNA (tRNA) uses its three-base anticodon to pair with the complementary mRNA codon.

4. Transfer RNA (tRNA) carries the correct amino acid to the ribosome.

5. Ribosomal RNA (rRNA) has enzymatic activity and helps form peptide bonds between amino acids.

What is true about the movement of molecules in aqueous solutions?

• Diffusion is the random movement of molecules from an area of higher concentration to an area of lower concentration.

• Osmosis is the net movement of water across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration.

• In a hypotonic solution, there is less solute outside the cell, causing the cell to swell and possibly lyse.

• In a hypertonic solution, there is more solute outside the cell, causing the cell to lose water and dehydrate.

• Adding salts to an aqueous solution decreases the relative concentration of water.

What are the characteristics of bacteria?

• Bacteria are the oldest known form of life existing today.

• Bacteria do not have a nucleus.

• Bacteria reproduce asexually.

• Bacteria do not have membrane-bound organelles.

What are the characteristics of protists?

• Protists may be single-celled organisms.

• Protists possess a nucleus.

• Some protists perform photosynthesis, while others ingest or absorb nutrients.

• Members of Kingdom Protista existed before plants, animals, and fungi.

What are the characteristics of plants, animals, and fungi?

• Plants convert light energy into chemical energy through photosynthesis.

• Fungi absorb nutrients from their surroundings.

• Animals ingest food.

• Plants, animals, and fungi are all eukaryotes with nuclei and membrane-bound organelles.

What is the function of the cell membrane?

The cell membrane regulates what enters and leaves the cell.

What gases made up Earth's early atmosphere?

• Nitrogen gas

• Water vapor

• Carbon dioxide

• Methane

What are true statements about Archaebacteria and Eubacteria?

• Archaebacteria live in extreme environments similar to ancient Earth.

• Eubacteria live in modern environments.

• A single bacterial cell can reproduce into billions of cells in as little as ten hours.

• Some bacteria form spores when conditions become harsh.

What are true statements about Archaebacteria and Eubacteria?

• Some bacteria require oxygen.

• Some bacteria cannot survive in oxygen.

• Some bacteria only survive in oxygen-rich environments.

• Some bacteria can survive with or without oxygen.

Why are bacteria important to Earth's environment?

• Bacteria produce nutrients through photosynthesis and chemosynthesis.

• Bacteria act as decomposers and recycle nutrients from dead organisms.

• Some bacteria produced Earth's first atmospheric oxygen.

• Bacteria are the only organisms that convert atmospheric nitrogen into usable forms for other organisms.

What are the most primitive organisms with a nucleus?

Protists are the most primitive organisms with a nucleus.

What is mitosis?

1. One nucleus divides.

2. Two genetically identical nuclei are produced.

What is meiosis?

1. One nucleus contains two copies of each chromosome.

2. The chromosome number is reduced by half.

3. Four nuclei are produced.

4. Each nucleus contains one copy of each chromosome.

What is alternation of generations?

1. An organism has a haploid (1n) phase.

2. An organism has a diploid (2n) phase.

3. The life cycle alternates between these two phases.

What is true about evolution?

• Meiosis increases genetic diversity by reducing chromosome number by half.

• The environment selects organisms with beneficial traits.

• Less competitive individuals are less likely to survive and reproduce.

• More competitive individuals pass their genes to the next generation.

• Species continue to evolve because environments change over time.

What are the different types of symbiotic relationships?

• Parasites harm their hosts.

• Commensalists benefit while not harming their hosts.

• Mutualists benefit both themselves and their hosts.

• Parasites can evolve into commensalists, and commensalists can evolve into mutualists.

• Lichens are a mutualistic relationship between algae and fungi.

• Mitochondria and chloroplasts may have originated as symbionts.

• The protist living in a termite's intestine is a mutualist.

• The protist that causes malaria is a parasite.

NA

NA

What are the characteristics of eukaryotic cells?

• Eukaryotic cells are highly compartmentalized.

• Cells take in particles through endocytosis.

• Cells release substances through exocytosis.

• Cells take in water by pinocytosis.

What are the characteristics of the cell membrane?

• The cell membrane is made of phospholipids.

• It contains hydrophilic and hydrophobic regions.

• It is selectively permeable.

• Nonpolar molecules pass through easily.

• Water passes through temporary gaps between fatty acid chains.

• Cholesterol affects membrane fluidity.

What is the function of the cytoskeleton?

• The cytoskeleton gives the cell its shape.

• It organizes cell components.

• It helps move organelles and chromosomes within the cell.

What are the functions of cell organelles?

• Peroxisomes contain catalase, which breaks down hydrogen peroxide.

• The smooth endoplasmic reticulum extends from the rough endoplasmic reticulum and does not contain ribosomes.

• The Golgi apparatus packages proteins for transport.

• Lysosomes contain digestive enzymes.

What occurs during the cell cycle?

• A cell may spend weeks or years in the G1 (Gap 1) phase.

• DNA replication occurs during the S phase.

• Proteins needed for mitosis are produced during the G2 (Gap 2) phase.

• Chromosomes separate during mitosis.

What must happen for a trait to evolve?

A trait must help an organism survive and reproduce in order to evolve within a species.

What occurs during the carbon cycle?

1. Autotrophs convert atmospheric carbon dioxide into organic molecules.

2. Heterotrophs obtain carbon by consuming other organisms.

3. Decomposers break down dead organisms.

4. Decomposers release carbon back into the atmosphere.

What is true about cellular respiration?

• Early organisms could perform anaerobic respiration but not aerobic respiration.

• Aerobic respiration produces more ATP than anaerobic respiration.

• Aerobic respiration can use sugars or fatty acids to produce ATP.

• Anaerobic respiration produces ATP from sugars.

• Aerobic respiration produces oxygen radicals that can mutate DNA.

What are the advantages of sexual and asexual reproduction?

• Asexual reproduction produces large numbers of offspring quickly.

• Sexual reproduction produces greater genetic diversity.

• Sexual reproduction allows offspring to inherit traits from all four grandparents.

What are the characteristics of fungi?

• Fungi are eukaryotes.

• Fungi reproduce sexually or asexually.

• Fungi act as decomposers in the carbon cycle.

• Fungi spend most of their life cycle as haploid (1n) organisms.

• Fungi can exist in parasitic and mutualistic relationships.