Edexcel A level biology Study guides, Class notes & Summaries

EDEXCEL A LEVEL BIOLOGY LASTEST 2024 UPDATED VERSION EXAM WITH COMPLETE QUESTIONS AND CORRECT ANSWERS 100% GUARANTEED A+ GRADED

What are tendons? - Answer Non-elastic fibrous tissue that anchor muscles to bones. What are ligaments? - Answer Elastic connective tissue that hold bones together and restrict the amount of movement possible at a joint. What is a joint? - Answer The point at which two or more bones meet. What are antagonistic muscles? - Answer Pairs of muscles which pull in opposite directions, i.e. as one muscle (agonist) contracts, the other (antagonist) relaxes. What are extensors? - ...

Biosphere -Answer part of the atmosphere and earth inhabited by living organisms Habitat -Answer Set of conditions where an organism lives Population -Answer All the organisms of one species in a habitat Population size/Abundance -Answer The number of individuals of one species in a particular area Carrying Capacity -Answer Maximum Stable population Distribution -Answer Where a species is within a particular area Community -Answer various populations...

What are target cells? - Answer Cells with receptor proteins on their cell surface membrane complimentary to the chemical What are meristems? - Answer Regions of actively dividing cells e.g. roots and shoots What do cytokinins do? - Answer promote cell division of stem and promote growth of lateral buds How do auxins cause cell elongation? - Answer Causes cell elongation by active transport of hydrogen ions into the cell walls, which lowers pH, making the cell walls flexible. Ce...

How do you investigate the effect of sucrose concentration on the growth of pollen tubes? - Answer 1. Make up solutions of sucrose between 0.2-2 moldm-3 2. Collect a petri dish for each sucrose concentration and place a moistened filter paper on each 3. Collect one microscope slide per concentration 4. Place a few drops of sucrose plus mineral salt medium in the dip of each slide 5. Gently rub the point of a mounted needle over the mature anthers of a flower so the pollen falls on the slid...

Exons - Answer the coding regions of DNA Introns - Answer the large, non-coding regions of DNA that are removed before messenger RNA is translated into proteins DNA (gene) sequencing - Answer the analysis of the individual base sequence along a DNA strand or an individual gene Polymerase Chain Reaction (PCR) - Answer the reaction used to amplify a sample of DNA, to make more copies of it more rapidly What happens when DNA is amplified? - Answer It is replicated repeatedly u...

Prokaryotic cell - Answer Cells that don't have a nucleus and other membrane bound organelles. Eukaryotic cell - Answer Cells with linear DNA inside nucleus, mitochondria present, larger ribosomes. Mitochondrion - Answer Inner of its two membranes folded to form finger-like projections called cristae. Site of aerobic respiration and produces ATP. Nucleus - Answer Enclosed by envelope composed of two membranes perforated by pores. Contains chromosomes and nucleolus. Nucle...

Water Potential - Answer Turgor Pressure + Osmotic Potential Diffusion - Answer The movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient. Facilitated diffusion - Answer Diffusion that takes place through carrier proteins or protein channels. The protein-lined pores of the cell membrane make facilitated diffusion possible. Osmosis - Answer The movement of water molecules from an area of high water potential to ...

Population - Answer Group of organisms of the same species in the same habitat at the same time Community - Answer A collection of all organisms of different species in the same place at the same time Ecosystem - Answer The interaction of different communities between each other and their habitat Biomes - Answer major ecosystems of the world Biosphere - Answer Hollow sphere where biomes are found Energy Flow Diagram - Answer - Progressively less energy available ...

What does homeostasis mean? - Answer Maintenance of a state of dynamic equilibrium What does homeostasis control? - Answer Constant internal environment, including constant temperature water potential and pH Why must temperature and pH be regulated? - Answer For optimum enzyme activity Why must water potential be regulated? - Answer To avoid negative osmotic effects which could damage a cell e.g lysis, shrinkage and disruption of metabolic reactions What does negative fee...