🤧 Flashcards
(36 cards)
How do the circulatory and respiratory systems work together?
The respiratory system brings oxygen into the lungs, and the circulatory system transports that oxygen through the blood to all body cells. This system interaction is essential for cellular respiration.
What is homeostasis and how does it work?
Homeostasis is maintaining stable internal conditions despite external changes. It works through negative feedback loops - when something changes (like blood sugar rising), the body responds to bring it back to normal (insulin lowers blood sugar).
How does DNA lead to cell function?
DNA contains instructions to build proteins. Different cells use different parts of the DNA to make specific proteins. The protein’s shape determines its function, which determines what the cell can do.
Why do different cells have different functions if they all have the same DNA?
All cells have the same DNA, but different genes are turned on or off in different cells (gene expression). This allows cells to specialize for different jobs even with identical genetic material.
What happens when an amino acid sequence changes due to a mutation?
If a mutation changes the protein’s shape, it can’t perform its function properly. This can disrupt cellular processes and affect the organism’s ability to maintain homeostasis.
What is photosynthesis and why is it important?
Photosynthesis converts light energy into chemical energy (glucose). Plants use CO₂ + water + light to make glucose + oxygen. It’s the starting point of all food chains and energy flow in ecosystems.
What is cellular respiration and why do all organisms need it?
Cellular respiration breaks down glucose using oxygen to release ATP (usable energy). Glucose + oxygen → CO₂ + water + ATP. All organisms need this to get energy for life processes.
How does energy flow through ecosystems?
Energy flows one direction from sun → producers → primary consumers → secondary consumers. Only about 10% of energy transfers to the next level; the rest is lost as heat. This explains why there are fewer organisms at higher levels.
What’s the difference between how matter and energy move through ecosystems?
Matter (like carbon and nitrogen) cycles through ecosystems and gets recycled. Energy flows one direction and is eventually lost as heat - it doesn’t get recycled.
How does carbon cycle through ecosystems?
Carbon enters ecosystems as COâ‚‚ through photosynthesis, moves through food chains, and returns to the atmosphere through cellular respiration, decomposition, and combustion.
What is carrying capacity and what determines it?
Carrying capacity is the maximum population size an environment can support long-term. It’s determined by available resources like food, water, space, and shelter.
What happens when a population exceeds its carrying capacity?
Resources become limited, organisms compete intensely, and some die or leave. The population typically crashes back down to or below the carrying capacity.
How does biodiversity affect ecosystem stability?
High biodiversity makes ecosystems more stable and resilient to changes. Low biodiversity makes ecosystems more vulnerable to collapse because there are fewer species to maintain ecosystem functions.
What are disturbances and how do they affect ecosystems?
Disturbances are events that disrupt ecosystem structure (fires, floods, deforestation, pollution). They can cause temporary changes that ecosystems recover from, or permanent alterations that create new ecosystem states.
Why do animals exhibit group behaviors like herding or pack hunting?
Group behaviors increase survival rates by providing protection from predators, more efficient hunting, cooperative care of young, and shared resources. Individuals in groups have higher fitness than those alone.
How do sexual and asexual reproduction differ in terms of genetic variation?
Asexual reproduction produces genetically identical offspring (clones) with variation only from mutations. Sexual reproduction creates genetic variation through meiosis and fertilization, producing unique offspring.
What is a mutation and how can it affect an organism?
A mutation is a change in DNA sequence. It can be harmful (disrupts protein function), beneficial (improves survival), or neutral (no effect). Only mutations in reproductive cells can be passed to offspring.
How does one fertilized egg become many different cell types?
Through cell differentiation - as cells divide, different genes are turned on or off in different cells, causing them to specialize for different functions even though they all have the same DNA.
How can environmental conditions affect gene expression?
Environmental factors can influence which genes are turned on or off without changing the DNA sequence itself. This can lead to different traits being expressed in different conditions.
What four conditions are required for natural selection to occur?
1) Variation must exist in the population, 2) Traits must be heritable, 3) There must be competition for survival/reproduction, and 4) Some traits must provide reproductive advantages.
What’s the difference between adaptation and fitness?
An adaptation is a specific trait that improves survival/reproduction in a particular environment. Fitness is the overall ability of an organism to survive and reproduce in its environment.
What evidence supports the idea that species share common ancestors?
Fossil records showing changes over time, homologous structures (same structure, different function), similar embryonic development, and DNA sequence similarities between related species.
How do populations evolve?
Individuals don’t evolve - populations do. Over many generations, advantageous traits become more common in the population while disadvantageous traits become less common, changing the population’s characteristics.
How do humans influence evolution?
Through artificial selection (breeding for desired traits), creating selection pressures (antibiotic resistance from overuse), and changing environments (climate change altering which traits are advantageous).
