Biology Lecture Notes: Plant Transport, Transport in Animals, Statistics, and Genetics

Comprehensive vocabulary flashcards covering plant and animal transport systems, statistical analysis in biology, genetics, immunology, and cell biology laboratory techniques based techniques like cell fractionation.

Transpiration

The loss of water from a plant's leaf by evaporation, which causes the upward movement of water in the xylem.

Cohesion-tension theory

A theory explaining the movement of water up xylem vessels in a continuous column; water molecules stick together via hydrogen bonds (cohesion) while evaporation from leaves creates a pulling force (tension).

Lignin

A substance that strengthens the cell walls of xylem and prevents water loss by evaporation.

Translocation

The movement of assimilates through the phloem from source to sink.

Sieve tube cells

Phloem cells containing sieve plates that reduce cell contents to decrease resistance to the flow of assimilates.

Mass flow hypothesis

A theory for sucrose movement where active transport of sucrose into the phloem lowers water potential, causing water to enter by osmosis from the xylem, creating high hydrostatic pressure at the source.

Tissue fluid

Fluid formed around cells when high hydrostatic pressure at the arteriole end of a capillary forces water and small substances out of the endothelium.

Co-transporters

A type of carrier protein used in both active transport and facilitated diffusion to move molecules across a membrane.

Null hypothesis

The statistical assumption that there is no significant difference and any results are due to chance.

T-test

A statistical test used when comparing two sets of data to see if there is a significant difference between two means.

Chi-squared

A statistical test used to compare expected and observed results.

Spearman's rank

A statistical test used to find the relationship or correlation between two variables.

Standard deviation

A measure of the spread of data about the mean that takes into account all values instead of just the range.

$PO_2$ (Partial Pressure of Oxygen)

A measure of oxygen concentration; haemoglobin's affinity for oxygen varies depending on this value.

Affinity

The ease with which haemoglobin binds and dissociates with oxygen.

The Bohr Effect

The process where a high concentration of $CO_2$ (high $pCO_2$) in the blood lowers haemoglobin's affinity for oxygen, causing the dissociation curve to shift right.

Stabilising selection

A type of natural selection that favors the average phenotype and selects against extremes, such as in human birth weight.

Disruptive selection

A type of natural selection that favors both extreme phenotypes while the intermediate phenotype is selected against.

Directional selection

A type of natural selection that favors one extreme phenotype.

Phylogeny

The study of the evolutionary history of groups of organisms, showing relatedness and common ancestors.

Binomial system

The nomenclature system for naming organisms using their Genus and species names.

Species

Organisms that can breed together to produce fertile offspring.

Community

All populations of all different species living in a habitat at a given time.

Niche

The specific role of a species within its habitat.

Carrying capacity

The maximum stable population size of a species that an ecosystem can support.

Interspecific competition

Competition for resources between members of two different species.

Intraspecific competition

Competition for resources between members of the same species.

Degenerate code

A feature of the genetic code where more than one triplet codon codes for the same amino acid.

Species richness

The number of different species in a community.

Index of diversity

A measure of biodiversity that accounts for both the number of different species in a community and the abundance of each species population.

DNA helicase

An enzyme that breaks the hydrogen bonds between bases, causing the DNA double helix to unwind during replication and transcription.

DNA polymerase

An enzyme that catalyses the formation of phosphodiester bonds between adjacent nucleotides during DNA replication.

Transcription

The process where RNA polymerase and DNA helicase produce an mRNA strand from a DNA antisense template strand.

Phagocytosis

A non-specific defense mechanism where a phagocyte engulfs a pathogen to form a phagosome, which then fuses with a lysosome for digestion.

B-cells

Cells involved in humoral immunity that divide by mitosis to form plasma cells, which produce antibodies, and memory B-cells.

Antigen presenting cell

A cell, such as a phagocyte that has engulfed a pathogen, that displays foreign antigens on its surface to activate T-cells.

Mitosis

A type of cell division resulting in two genetically identical daughter cells, consisting of prophase, metaphase, anaphase, and telophase.

Crossing over

A process during meiosis where non-sister chromatids from homologous chromosomes exchange sections at chiasmata, increasing genetic variation.

Independent segregation

The random distribution of maternal and paternal chromosomes into gametes during meiosis.

Homogenisation

The process of grinding cells in a blender to break the plasma membrane and release organelles into a solution.

Ultracentrifugation

The process of spinning a filtered homogenate (filtrate) at increasing speeds to isolate organelles based on their weight.

Micelles

Structures formed by bile salts, fatty acids, and monoglycerides that assist in the absorption of lipids into epithelial cells.

Chylomicrons

Lipid packages created by the Golgi apparatus that leave epithelial cells by exocytosis to enter the lacteal and eventually the bloodstream.