Answer:
4, 3 5, 1, 2.
Explanation:
The events of muscle contraction begins from the presynaptic neuron, which cause the influx of Ca+, and the release of acetycholine neurotransmitter into the synaptic cleft.
The Ach, binds with the receptors in the sarcolemma, leading to opening of Ligand gated Na+ channels. Therefore Na+diffuses in, causing depolarization, and propagation of action potential along the sarcolemma spreading to the T-tubules.
This is followed by opening of Calcium channels leading exist of Ca+ from the sarcoplasmic reticulum.
The Calcium binds with the troponin, and Tropomysoin exposed the myosin binding sites on the actin filament.Thus cross-bridge is formed by the myosin head with thin filaments which shortened the sarcomere, leading to contraction of muscle fibres.
The black widow spider is an invertebrate. Its skeleton system hangs outside its body. The only difference between a vertebrate and invertebrate is the presence of backbone or a similar kind of structure with in the body. In case of black widow spider, the internal structural element is missing. Its skeleton system can be classified as exoskeleton.
Innate: keratinized epithelium
stratified squamous epithelium hypodermal areolar connective tissue antigen presenting cells major histocompatibility complexes complement (antibody -dependent pathway )
Innate or non-specific response is the first defense against invaders. Components of this response include physical (e.g. skin . mucosa) and chemical barriers against pathogens and cells such as Natural Killer cells, macrophages, neutrophils, dendritic cells, mast cells, basophils, eosinophils. Innate response reacts immediately.
Adaptive: immunoglobulin plasma cells agglutinin
helper t cells memory t cells cytotoxic t cells cd4+cells
t lymphocytes
Adaptive immune response or specific response is specific to the pathogen presented and mediated by lymphocytes, B and T cells. Adaptive immune response creates immunological memory after the first, initial l response to a specific pathogen which leads to enhanced response.
<h2>Mutation & genetic drift</h2>
Explanation:
- A mutation is characterized as a lasting change to the DNA succession in a quality. This change moves the hereditary message conveyed by the quality and can modify the amino corrosive arrangement of the protein the quality encodes. This implies future cells created by the quality will just convey a specific characteristic.
- Genetic Drift is the change in the hereditary structure of a populace after some time because of possibility or irregular occasions. In instances of hereditary float, for example, catastrophic events or periods of irregular climate, the age that makes due to repeat won't really be the fittest, yet the most fortunate. Hereditary float doesn't allude to a particular change in hereditary cells, rather to arbitrary events that impact a population's genetic makeup.
- Hence, the right answer of the fill up the blank is "mutation and genetic drift".
