Biology

🔬 Conversion of Ocular Micrometers, Lesson Written by Ilysse Baum, Queens College 📖

  • This lesson explains how to use the "Metric Staircase" to convert ocular micrometers, which is covered in our Introductory Biology labs at Queens College.

  • This video provides an explanation of Punnett Squares with examples of how to calculate the probability of an offspring with certain characteristics, such as eye color. It explains how to do a monohybrid cross and a dihybrid cross, and discusses the difference between the dominant allele and the recessive allele. Terms such as homozygous dominant, heterozygous and homozygous recessive are also covered, as well as an explanation of how to calculate the genotype ratio and the phenotype ratio.

  • This study guide provides an explanation of empirical and theoretical probabilities, and how to apply the product and sum probability rules to dihybrid crosses.

  • The Shannon Diversity Index (H) is an index commonly used to characterize species diversity in a community. This video discusses the terms of abundance, species richness, and diversity and illustrates how to calculate the Shannon Diversity Index.

  • This video shows how to use Google Sheets and Excel to calculate the Shannon Diversity Index.

  • This video explains Simpson's Diversity Index, a measure of diversity which takes into account the number of species present, as well as the relative abundance of each species. As species richness and evenness increase, so diversity increases.

  • This video provides an explanation the Hardy-Weinberg Equation, which states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.

  • This video explains how the surface area to volume ratio affects how large cells can be. It also details why transport systems are needed to provide materials to the many cells that make up multicellular organisms.

  • The video defines pH as a scale used to specify how acidic or basic a water-based solution is. Mathematically, pH is defined as the negative common logarithm of the activity of a hydrogen ion in a solution. This video also describes pOH, a measure of the hydroxide ion (OH-) concentration, which is used to express the alkalinity of a solution. Reversible reactions, the water dissociation constant, acids, bases, and neutral solutions, and strong and weak acids are also discussed.

  • This video explains the difference between a linear scale and a logarithmic scale. On a linear scale, the value between any two points will never change. A logarithmic scale is one in which the units on the axis are powers, or logarithms, of a base number. Exponential growth curves are displayed on a logarithmic scale.

  • This video tutorial explains how to solve exponential growth and decay word problems.

  • This video provides an example of the radioactive decay of a substance, as well as an application of exponential growth to a fast-food restaurant chain.

  • This video explains the five basic steps of the scientific method: (1) make an observation, (2) ask a question, (3) form a hypothesis, or testable explanation, (4) make a prediction based on the hypothesis, and (5) test the prediction. We then iterate, and use the results to make new hypotheses or predictions.

  • This video applies the principle of hypothesis testing to a practical example: siblings washing their dinner dishes.

  • This video defines explanatory and response variables, as well as control and treatment groups.

  • This video explains how to identify the difference between independent and dependent variables as well as constants in experiments.

  • This video explains how the independent variable influences change in the dependent variable using a practical example: plant growth.

  • This video explains how to identify, and plot, the independent and dependent variables on a graph (a Cartesian plane). The independent variable goes on the horizontal x-axis, and the dependent variable goes on the vertical y-axis. It also shows the relationships of certain graphs such as: linear curves, inverse relationships, and quadratic or parabolic functions, using the examples of Boyle's law of pressure and volume in chemistry, Newton's second law of motion between force, mass, and acceleration in physics, and distance vs. time under constant acceleration in physics.

  • This study guide defines and provides examples of controlled experiments, control and experimental groups, independent and dependent variables, variability and repetition, and sample size.

🔵 Biología Humana, Human Biology Khan Academy Videos en Español 📺