Honors Biology - FINALS

What are the basic components of all cells?

Ribosomes → where translation occurs for protein synthesis

Cell Membrane → phospholipid bilayer that regulates movement in and out of the cell

Cytoplasm → where most metabolism occurs

DNA → universal genetic code/herediatary material

• For Eukaryotes, DNA is in the nucleus

• For Prokaryoties, DNA floating around (no nucleus)

Describe the structure and function of key organelles (ER, Golgi, mitochondria, lysosomes, nucleus).

Endoplasmic Reticulum → series of membranes that allows material to travel through the cell

Golgi Apparatus → stack of flat membranes that packs and prepares materials to be sent and secreted out of the cell

Mitochondria → membrane-bound organelle that provides energy to the cell through cellular respiration (creating ATP)

Lysosomes → membrane-bound organelle that contains enzymes that break down food, old cell parts, and bacteria

Nucleus → membrane-bound organelle that contains DNA (genetic material)

Why are cell membranes important for homeostasis?

• Cell membranes control what goes in (like water, nutrients) and out (waste) of the cell, maintaining an internal environment separate from the external environment.

• They keep the internal environment stable and balanced.

What roles do transmembrane proteins play in the cell membrane?

• Transport → protein pumps, carriers, and channels help move substances across the membrane

• Enzymes → catalyze reactions inside the cell

• Identity Markers → glycoproteins, glycolipids use their carbohydrate antenna to detect their surroundings

  • Used in cell-to-cell recognition, helps them to determine what is self and what is foreign

• Receptor → receive external chemical signals to activate signal transduction pathways

• Cell Junctions → connect one cell to another

• Structure → maintain cellular shape and assist in movement

How does the surface area to volume ratio impact cell efficiency?

Small cells have a larger surface area with a smaller volume

• More membrane means more area available for exchange, with less cytoplasm means less area for things such as nutrients to travel, which allows for a more efficient exchange rate with the environment

Explain the difference between active and passive transport across the membrane. (Including Osmosis, Diffusion, Facilitated Diffusion)

ACTIVE TRANSPORT → requires ATP to move ions/bulk substances against the across the membrane while going against the gradient

• EX> Protein Pumps & Bulk Transport

PASSIVE TRANSPORT → does NOT require ATP to move substances across the membrane while going with the gradient

• Simple Diffusion: happens with small, uncharged nonpolar molecules (O₂ or CO₂) that pass through the membrane easily

• Facilitated Diffusion: happens with medium-sized, charged polar molecules (K⁺ or Na⁺) that use protein channels or carriers to pass through membrane

• Osmosis: refers to the movement of H₂O through the membrane using protein channels called aquaporins

Recall that in dialysis tubing, the size of the membrane pores is critical in determining the movement of molecules

In dialysis tubing, the size of the membrane pores determines which molecules can pass through—only molecules with a smaller size (water or glucose) can diffuse, while larger ones like starch are blocked.

Why can’t cells use glucose directly for energy?

Breaking down glucose would release too much energy at once, which would overwhelm cells and potentially kill them

• This is because metabolic pathways have evolved to slowly release and store energy without damaging the cell

ATP is more energy efficient since it stores and releases smaller packets of energy, so none is wasted

Describe the ATP cycle and its role in cellular processes.

ATP CYCLE

1. ATP hydrolyzes (dephosphorylated) and energy is released, which is to used for cellular work

2. ADP is "re-phosphorylated” with energy that came from the breaking of glucoses’ bonds from cellular respiration

ATP provides energy for 3 types of cellular work

1. Chemical: synthesis reactions (DNA/protein synthesis)

2. Mechanical: movement of muscles

3. Transport: movement of ions (against gradient

Compare and contrast photosynthesis and cellular respiration. Which organisms perform each process?

PHOTOSYNTHESIS

• Purpose: To convert light energy into chemical energy (organic compound glucose)

• Who: Autotrophs with photosynthetic pigments

• Reactants: sunlight + H₂O + CO₂

• Products: C₆H₁₂O₆ + O₂

• Location: Chloroplast

• Energy Transformation: light energy to chemical energy

• Relationship: provides glucose and oxygen for respiration

CELLULAR RESPIRATION

• Purpose: to break down glucose to release usable chemical energy in the form of ATP

• Who: ALL EUKARYOTES

• Reactants: O₂ + C₆H₁₂O₆

• Products: H₂O + CO₂ + ATP

• Location: Cytoplasm (glycolsis) & Mitochondria

• Energy Transformation: chemical energy to chemical energy

• Relationship: provides CO₂ and water for photosynthesis

In general happens during aerobic vs. anaerobic respiration – what are the reactants and overall products? (Intermediate steps or numbers of products/ intermediates are NOT required)

AEROBIC RESPIRATION

• Uses O₂ and Glucose

• Produces ATP, CO₂, & H₂O

• Releases the maximum amount of energy since it breaks down all glucose bonds (oxidized)

ANAEROBIC RESPIRATION

• Only occurs when O₂ is absent

• Starts with only glucose

• Produces a minimal amount of ATP along with a variety of other byproducts depending on the organism

  • For humans, this respiration produces lactic acid

  • For yeast, it is ethanol (this is what produces our alcohol)

• Very little energy is released since only a few glucose bonds are broken (oxidized)

How do light, pigments, and wavelength affect photosynthesis? Know how to read an absorption spectrum, and what that means for energy absorption/ reflection.

Light → powers photosynthesis

Pigments → more pigments = more energy can be absorbed = more reactants for photosynthesis = more photosynthesis occurs = more glucose production!

Wavelength → depending on the measure of the wavelength, plants either reflect or absorb that energy

• The more light absorbed, the less visible the red that associated with that wavelength meassure is

• The less light absorbed, the more visible the color associated with that wavelength is

What is the difference between energy flow and nutrient cycling in ecosystems? Which organisms are involved in decomposition and recycling?

Energy flow refers to the transfering up of energy through trophic levels, starting with the primary producers. Energy is not recyclable—it is lost as heat or used up in the life processes of the organisms at each level.

Nutrient cycling refers to the continuous recycling of nutrients (carbon, nitrogen, and water) through all trophic levels back to producers at the first trophic level

Decomposers are responsible for decomposition and recycling, so this includes bacteria and fungi

Explain trophic levels and the 10% energy rule.

Trophic levels divide ecosystems up into 4 categories

1. Primary producers

2. Primary consumers

3. Secondary consumers

4. Tertiary Consumers

In each ecosystem, only 10% of energy from the previous trophic level is passed to the next because the other 90% is used up by the previous organisms through performing the life processes or lost as heat or just secreted out.

Understand the consequences of removal of an organism from an ecosystem/ food web.

Typically, if even one organism is removed, a detrimental ripple effect will occur and will impact the whole ecosystem

• If a predator is removed, prey populations may grow too large, leading to overgrazing or depletion of resources

• If a prey or producer is removed, predators may starve or be forced to compete more, possibly causing declines or extinction

• If a decomposer is removed, waste and dead matter would build up, and nutrient cycling would slow down, harming plant growth

Define and give examples of symbiotic relationships (mutualism, commensalism, parasitism). 

• Mutualism: both organisms benefit

  • Bees and Flowers → bees get nectar from flower while flower gets pollinated

• Commensalism: one organism benefits, other is unaffected

  • Barnacles and Whales → barnacles ride on whales for transport while whale dont care

• Parasitism: one organism is negatively affected, other is positively affected

  • Tick and Dog → Tick feeds on dog's blood and causes disease

What is biomagnification, and why are top predators at risk?

It is the process where toxic substances (DDT or mercury) become more magnified or concentrated when moved up the food chain or up trophic levels.

Top predators at risk because this process occurs when toxic substances build in organisms in lower trophic levels, and then when organisms from higher trophic level consume those organisms, they inherit more and more of the toxic substances from them. This means that the higher up the food chain, the more toxic substances that have been accumulated in the top predator's diet, meaning they are at the highest risk.

How does human interventions, like deforestation and logging impact ecosystems and biodiversity?

Deforestation and logging contribute to habitat loss, which is one of the biggest threats to ecosystems today.

These interventions destroy natural habitats that animals and plants need to survive, leading to biodiversity loss because species no longer have the space or resources to live

With lower biodiversity, ecosystems are far less stable and less likely to survive any environmental changes

What is the expected genotypic and phenotypic ratio for multiple types of genetic crosses:

• Monohybrid

• Dihybrid

• Incomplete dominance

• Multiple Alleles

MONOHYBRID

• Aa x Aa

  • For Genotype Ratio and Phenotype Ratio set up a punnett square

DIHYBRID

• BbCc x BbCc

  • Genotype and Phenotype Ratio: 9 dominant dominant : 3 dominant recessive : 3 recessive dominant : 1 recessive recessive

Incomplete Dominance

• RR x WW

  • For Genotype and Phenotype Ratio set up punnett square

    • When both dominant traits are combined (WR), it is a mix of the two traits

Multiple Alleles

• Have three or more forms that exist in a population, BUT one individual will only have 2 alleles at a time

• The key will have 3 letters usually two capitals with a superscript and one lowercase

• For Genotype and Phenotype set up punnett square