4. An animal that relies on a digestive tract for digestion breaks down food bya. both intracellular and extracellular digestion.b. extracellular digestion onlyc. neither intracellular nor extracellular digestion.d. intracellular digestion only

Answer:

Cytochrome C; it provides evidences that there is similarities in the respiratory pathways for producing ATPs by  all living organisms especially mammals.

Explanation:

Cytochrome c is located in the intermembranes of mitochondria, and it functions in the transfer of  of one electron in electron transport chain,(ETC) needed for  generation of proton motive force;  for generation of energy in the synthesis of ATPs by ATPase synthase  during chemiosmosis. Its allows oxdation-reduction by the switching of its iron ii to iron iii. during electron transports.However its iron atoms does not undergo oxidation with  oxygen. This feature makes it stable and  an ideal carrier of electrons.

Its amino acid sequences is very similar in all living organisms especially  between mammals(e.g man and chimpanzees)with little variation in few amino acid residues due to mutation.This similarity in its amino acids sequences in all  living  organism together with small molecular size makes it ideal  molecular evidence  for studying comparative molecular evidence of  evolution.

This is because it can be used  to trace  the pathways of respiration to synthesize energy, and therefore to conclude that  most  organisms share common ancestry, since a very similar protein sequence in  a structure(Cytochrome c) participated in unique ETC mechanisms  in all, needed for energy synthesis .

Final answer:

The pericardium or pericardial sac is a membrane that surrounds the heart, consisting of the fibrous pericardium and the serous pericardium. The serous pericardium further has a parietal layer and a visceral layer or epicardium, which secretes a lubricating fluid.

Explanation:

The pericardium, also known as the pericardial sac, is a membrane that directly surrounds the heart and defines the pericardial cavity. It consists of two distinct sublayers: the sturdy outer fibrous pericardium and the inner serous pericardium. The fibrous pericardium, made of tough, dense connective tissue, protects the heart and maintains its position in the thorax. The serous pericardium has two layers, namely the parietal pericardium, which is fused to the fibrous pericardium, and an inner visceral pericardium, or epicardium, which is fused to the heart.

The macroscopic epicardium layer consists of a simple squamous epithelium called a mesothelium, reinforced with loose, irregular, or areolar connective tissue that attaches to the pericardium. This mesothelium secretes the lubricating serous fluid that fills the pericardial cavity and reduces friction as the heart contracts.

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The alternation of generations in the life cycle of a plant includes the diploid and haploid multicellular stages. diploid and haploid are copies of the chromosomes. The spores in the plant is unicellular and when they start dividing through mitosis, it produces identical cells. These identical cells are all haploid. Haploid stages contain one set of chromosome from either of the parent. These identical cells create a multicellular system called the gametophytes. A gametophyte is the haploid multicellular stage in the life cycle of a plant. The gametophyte makes the gametes. These gametes are responsible for sexual fertilization. It takes place when a sperm (male gametes) from the male fuses into the egg cell (female gametes) of the female. The formation of both male and female gametes creates a diploid zygote. Diploid stages contain one set of chromosome from each parent. This is where the sporophyte comes in. A sporophyte is the diploid multicellular stage in the life cycle of the plant. It now contains the two sets of chromosomes from each parent.

The type of cell division that produces gametes with half the normal chromosome number is the meiosis. Meiosis is the type of cell division used in sexual reproduction. It will occur in the testes and ovaries.