<u>Answer:</u>
Free-living flatworms have developed a nervous system which helps them to sense the food. They have a head at one end of the body and each side of the head has sensory cells. These cells help them to sense chemicals and other movements around them.
While Parasitic flatworms don't have any nervous or digestive system as they live on the food digested by the host. They have special hooks attached to their head which help them to attach a host. They have developed some covering called 'teguments' which protect them from digestive liquids.
Answer:
The correct answer would be "Myosin heads attach to sites on actin filaments".
The muscle cell or myofibril consists of two types of protein filaments namely; actin (thin filament) and myosin (thick filament).
The myosin heads attach to the binding sites on the actin filaments and pull it towards the M-line in order to produce contraction.
The hydrolysis of ATP provides energy for this contraction cycle.
When an animal's oxygen supply is limited, bisphospoglyceric acid increases the oxygen level by acclamitization.
Acclimatization is the term used to describe the advantageous physiological changes brought on by frequent exposure to a hot climate. Increased sweating effectiveness is one of these physiological modifications. It is converted into a molecule identical to that of 2,3-bisphosphoglyceric acid (2,3BPG). A mechanism called 2,3BPG is employed to control the effective emission of oxygen from haemoglobin. As one of the processes of acclimatization, 1,3-BPG levels will rise in a patient's blood when concentration is low. Low oxygen levels increase 1,3BPG levels, which in turn increase 2,3BPG levels and change how well oxygen separates from hemoglobin.
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<span>During Glycolysis, one molecule of glucose is converted into two molecules of pyruvic acid in the cytoplasm of the cell. Pyruvic acid is then moved into the inner matrix of the mitochondria, which is the organelle within the cell responsible for the generation of energy. The pyruvic acid molecule is converted into acetyl Co-A, which is the molecule that enters the Krebs Cycle. In the Krebs Cycle, acetyl Co-A is attached to oxaloacetate acid to form citric acid; the Krebs Cycle is alternately known as the citric acid cycle.</span>
It carries impulses to the neuron cell body