Answer:A. The release of calcium ions causes myosin and actin to attach to each other.
The contraction of skeletal muscles takes place by induction of a nerve impulse, which produces a movement and the interaction of the filaments containing proteins named as actin and myosin. This interaction of filaments is regulated by proteins called tropomyosin and troponin present on the actin filaments. The motor nerve causes the depolarization of the muscle membrane sarcolemma. This triggers the sarcoplasmic reticulum to release calcium ions. This calcium binds to troponin and thus allows the tropomyosine strand on the actin filament to displace so that the part of the actin where myosine head needs to be attached remain uncovered. Binding of the actin myosine filament results in contraction.
Hence, the release of calcium ions causes myosin and actin to attach to each other causes muscle contraction.
The answer is that <span>all
veins carry blood back to the heart, except for the pulmonary vein. the
vena cava empty into the right side of the heart, so they technically
bring blood to the
</span>main atrium.
Answer:
Please find the explanation below
Explanation:
Sexual reproduction is the kind of reproduction that requires two organisms (male and female) to form an offspring. The male organism produces gametes called SPERM while the female organism produces gametes called EGG. These two gametes come together in a process called FERTILIZATION to produce a zygote, which develops into an offspring.
In sexual reproduction, gametes are produced by organisms involved via a process called MEIOSIS. Meiosis, however, reduces the chromosome number of the gametes by half. However, one process unique to only meiosis and sexual reproduction is called CROSSING OVER.
Crossing over is the process whereby chromosome segments is exchanged between non-sister chromatids of homologous chromosome. This process causes a recombination of chromosomes (alleles) in such a way that the gametes will be genetically different from the parent organisms (genetic variation). According to this question, sexual reproduction leads to more genetic variation than asexual reproduction due to the process of CROSSING OVER that occurs in sexual reproduction.
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Question 2
D) Carbohydrates
