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Biology: explore STEM content (page 32 of 50) · openstem
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Search the community's STEM library — free to study, yours to make your own.
Biology
Cells, genetics, ecology and physiology on openstem — flashcards, notes, quizzes, sketches and flowcharts shared by the community. Study free, or clone anything into your library.
What are the three main types of vaccines described here?1 / 10
Weakened (live-attenuated) vaccines, inactivated (killed) vaccines, and mRNA vaccines — three different ways scientists teach your immune system to recognize a germ.
The Five Kingdoms at a Glance Scientists classify — or sort — every living thing on Earth into one of five kingdoms. Organisms end up in the same kingdom because they share important features, such as how they get their food or what their c
Incomplete lineage sorting is expected to be most prevalent, causing the greatest gene tree/species tree discordance, under which combination of conditions?
AWidely spaced speciation events and small ancestral effective population size.BClosely spaced speciation events in time combined with large ancestral effective population size.CILS frequency is completely independent of speciation timing or population size.DOnly when hybridization has occurred between the species in question.
Biology
Biology · L5 · Phylogenomics and Comparative Genomics
Food Chains in Nature A food chain shows how living things get their energy. Energy moves from one living thing to the next. How a Food Chain Works Most food chains start with the Sun. Plants use sunlight to make their own food. Then animal
What is the main structural difference between prokaryotic and eukaryotic cells?1 / 11
Prokaryotic cells (bacteria, archaea) lack a membrane-bound nucleus; their DNA is in the cytoplasm as a nucleoid region. Eukaryotic cells (animals, plants, fungi, protists) have a membrane-bound nucleus plus membrane-bound organelles (mitochondria, ER, Golgi, etc.).
What is habitat loss, and why is it considered the single greatest threat to biodiversity?1 / 10
Habitat loss is the destruction, fragmentation, or degradation of the natural environment a species depends on, usually through logging, agriculture, or urban development. It is the leading threat to biodiversity because a species that loses its habitat loses its food, shelter, and breeding grounds all at once.
Biology
Biology · L3 · Threats to Biodiversity and Conservation Strategies
What does the Michaelis-Menten equation describe, and what is its general mathematical form?1 / 10
The Michaelis-Menten equation describes how the initial reaction rate (v) of an enzyme-catalyzed reaction depends on substrate concentration ([S]) at a fixed enzyme concentration. Its form is v = (Vmax[S]) / (Km + [S]), which produces a rectangular hyperbola when v is plotted against [S]: rate rises steeply at low substrate concentration and levels off as the enzyme's active sites become saturated.
The endocrine system The endocrine system is a network of glands that secrete chemical messengers called hormones directly into the bloodstream. Unlike the nervous system, which sends fast electrical signals along neurons to specific target
Describe how RIG-I-like receptors (RIG-I, MDA5) distinguish viral RNA from host RNA in the cytoplasm, and the downstream signaling that leads to type I interferon production.1 / 9
RIG-I preferentially recognizes short double-stranded RNA bearing an uncapped 5' triphosphate or diphosphate group, a chemical signature present on many viral RNA replication intermediates but absent from host cytoplasmic mRNA, which is 5' capped; MDA5 instead recognizes longer double-stranded RNA structures, together giving the RIG-I-like receptor family broad but discriminating coverage of RNA virus replication intermediates.
How does a strawberry plant use runners to spread?1 / 10
A strawberry plant sends out long, thin runners across the soil surface. Where a runner touches the ground, it can grow its own roots downward and a new shoot upward, becoming a separate strawberry plant.
Biology
Biology · L2 · Runners, Tubers, and Cuttings in Action
An allergen is a normally harmless substance — such as pollen, peanut protein, pet dander, or dust mite droppings — that triggers an unnecessary immune response in someone who is allergic to it.
Biology
Biology · L3 · Allergies: The IgE-Histamine Pathway
Speciation Mechanisms Speciation is the process by which one lineage splits into two or more reproductively isolated groups. Under the biological species concept, the defining criterion is not morphological difference but the inability to p
Does a butterfly go through complete or incomplete metamorphosis?1 / 10
Complete metamorphosis. A butterfly egg hatches into a caterpillar (the larva), which forms a chrysalis (the pupa), and an adult butterfly emerges from the chrysalis.
Biology
Biology · L2 · Metamorphosis in Action: Insect Examples
What does a biodiversity index measure, conceptually?1 / 9
A biodiversity index combines two properties of a community into a single value: species richness (the number of different species present) and species evenness (how evenly individuals are distributed among those species). A community with many species that are all similarly abundant scores higher in diversity than one with the same number of species but dominated by just one or two of them.
Biology
Biology · L4 · Ecosystem Ecology and Conservation Biology
AA disease that only affects some childrenBThe stage of life when a child's body gradually matures into an adult bodyCA single day when the body suddenly becomes an adultDA stage that only happens to some people, not everyone
Biology
Biology · L2 · Growing Up and Reproduction Basics Quiz
Cellular respiration is the process cells use to release the energy stored in food (glucose) so they can power everything they do — moving, growing, and repairing themselves.
Biology
Biology · L2 · Cellular Respiration: The Word Equation
Distinguish a proto-oncogene from an oncogene in terms of gene dosage and dominance.1 / 10
A proto-oncogene is a normal cellular gene (often encoding a growth factor, receptor, signal transducer, or transcription factor) that promotes proliferation under tight regulatory control. An oncogene is a mutant, constitutively active or overexpressed allele of that gene. Oncogenic activation is functionally dominant — a single mutant allele, in the presence of a normal wild-type allele, is sufficient to drive transformation, in contrast to the typically recessive behavior of tumor-suppressor loss.