Correct Answer: (2) protein

Meat is composed of proteins. When proteins are ingested, the initial digestion occurs in the stomach, where the protein is converted into small polypeptides with the help of an enzyme called pepsin. Then the protein goes to the small intestines, where most of the digestion process occurs. The small polypeptides are further broken down into smaller polypeptides with the help of the enzymes trypsin and chymotrypsin. Then these polypeptides are again broken down into amino acids, which are highly complex organic compounds. Digestion of meat takes around 30 minutes to less than a day, depending on several factors such as type of meat and rate of metabolism of the individual. After three days, the meat protein will have been converted to amino acids, and then distributed to different parts of the body; some of the amino acids are again formed into proteins to perform specific functions inside the body.

Incorrect Answers:

(1) glucose

There are four types of macrobiomolecules: protein, carbohydrate, nucleic acid, and fat. Each of these undergoes different pathways of digestion. Since meat is composed mostly of protein, then the product of meat digestion is amino acid or protein (after three days). Glucose is a simple sugar produced from carbohydrates, which is different from proteins.

(3) starch

Starch is a polysaccharide. In the initial stage of digesting carbohydrates, they are broken down inside the oral cavity into simpler and smaller polysaccharides like maltose. Proteins cannot be converted into complex sugars like starch.

(4) oxygen

Oxygen enters the body through respiration and distributed through the circulation of blood. It is not a product of meat digestion.

Correct Answer: (3) circulatory-transports materials for energy release in body cells

The circulatory system transports nutrients, gases, hormones, blood cells, nitrogen waste products, from cell to cell of the body to help fight diseases, help stabilize body temperature and pH to maintain homeostasis.

Incorrect Answers:

(1) excretory-produces antibodies to fight disease-causing organisms

The excretory system is involved in the disposal of nitrogen-containing waste products of metabolism. The immune system composed of special cells, proteins, tissues, and organs, is responsible for the formation of antibodies and defense against disease.

(2) digestive-produces hormones for storage and insulation

The digestive system is the organ system involved in the breaking down of food into molecules small enough for the body to absorb. It is the endocrine system that is involved in the production of hormones for storage and insulation.

(4) respiratory-collects waste material for digestion

The respiratory system is responsible for oxygenation of blood to be distributed to the different parts of the body. The excretory system is the organ system in charge of the elimination of the waste products of metabolism.

A hormone is a chemical signal secreted into body fluids (like blood) by specialized cells. A certain hormone may reach all parts of the body but only specific types of cells called target cells which are equipped to react with them. When the target cells recognize the presence of the hormone, they bind to receptor proteins located in the cytoplasm and/or nucleus. This now forms the hormone-receptor complex that binds to particular sequences of DNA serving as transcription factors regulating a particular response.

(1)These cells have different DNA than the cells in other body systems.

Deoxyribonucleic acid (DNA) carries all the genetic instructions for the development and functioning of organ. Though it is true that the cells in the sex cells are different from the rest of the body cells, this does not directly affect the cell-hormone relationship.

(3) Reproductive system cells could be harmed if they made contact with hormones from other body systems.

Non-target reproductive cells are not affected by the hormones because of the absence of receptors. When the receptors are absent, the hormone cannot bind with the cell and cause any positive or negative reaction.

(4) Cells associated with the female reproductive system only respond to the hormone testosterone.

Testosterone, a predominant androgen hormone in the male body, is just one among a number of hormones present in the human body. And just like any other hormone, testosterone only affects its target cells, which are most found in the male body.

The structure B is the plasma membrane. It is a semi-permeable membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the entrance of materials and exit of wastes in the cell.  The waste products move out of the cell usually through osmosis.

(1) A

This is the nucleus. It is the organelle that contains the genetic material of the plant cell.

(3) C

These structures are called vacuoles, which store food, water, minerals, and wastes. In plant cells, vacuoles are larger to contribute in the rigidity of the cell.

(4) D

D illustrates the mitochondrion (mitochondria, plural) or the powerhouse of the cell. It is responsible for the release of energy for all the cellular functions.

The vacuole is a membrane-enclosed cell organelle that is responsible for the storage of water, food, minerals, and waste in the cell.

Incorrect Answers:

(2) coordination

The nucleus is known as the control center of all activities of the cell. Hence, it is responsible for coordination.

(3) synthesis of molecules

Ribosome, a cell organelle constructed in the nucleolus, is the site of protein synthesis in the cytoplasm.

(4) release of energy

It is the center of cell respiration, thus it is regarded as the powerhouse of the cell and responsible for releasing energy for all cell functions.

A nucleus (structure C) is the biggest organelle in the eukaryotic cell. The normal size of a nucleus is 900 to 100nm. It contains the chromosome (structure B), which is a long threadlike association of genes (structure A).

Incorrect answers:

(1) chromosome that is part of structure C

The chromosome is not the smallest among the three structures; although, it is correct that the chromosome is part of structure C, which is the nucleus.

(2) chromosome that contains B and C

The chromosome is neither the smallest structure among the three nor does it contain structure C or the nucleus. It is the nucleus that contains structure B (chromosome), where genes are present.

(3) nucleus that contains both structure B and structure A

The organelle X represents the mitochondrion. It is the organelle found in eukaryotic cells that performs cellular respiration or the process wherein biochemical energy from nutrients are transformed into adenosine triphosphate (ATP).

The main components of the process are glucose and oxygen. The products of cellular respiration are carbon dioxide, water, and energy (ATP). ATP, the energy currency of the cells, will be used in endergonic reactions in cells.