Systems Biology
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GED Science › Systems Biology
Which of the following cells only contains a single copy of each chromosome?
Oocyte
Neuron
Lymphocyte
Erythrocyte
Explanation
The germ cells (eggs/oocytes and sperm) contain only one copy of each chromosome. This reduction in the amount of DNA occurs through meiosis. Most cells in the body contain two copies of each chromosome and are considered diploid. Since they only contain ne copy of each chromosome, germ cells are considered haploid.
Neurons and lymphocytes (white blood cells) contain two copies of each chromosome; they are diploid. Erythrocytes (red blood cells) do not have nuclei, and do not contain any genetic material.
Which of the following cells only contains a single copy of each chromosome?
Oocyte
Neuron
Lymphocyte
Erythrocyte
Explanation
The germ cells (eggs/oocytes and sperm) contain only one copy of each chromosome. This reduction in the amount of DNA occurs through meiosis. Most cells in the body contain two copies of each chromosome and are considered diploid. Since they only contain ne copy of each chromosome, germ cells are considered haploid.
Neurons and lymphocytes (white blood cells) contain two copies of each chromosome; they are diploid. Erythrocytes (red blood cells) do not have nuclei, and do not contain any genetic material.
What class of hormone must attach to membrane-bound receptors?
Peptide hormones
Steroid hormones
Tyrosine derivative hormones
Cholesterol hormones
Explanation
There are three primary types of hormones: peptide hormones, steroid hormones, and tyrosine derivative hormones. Of the three, peptide hormones are the only polar hormones, so they cannot pass the cell membrane. As a result, they must attach to a membrane-bound receptor in order to elicit a response in the cell.
Tyrosine derivatives and steroid hormones are smaller, nonpolar molecules. This allows them to pass directly through the membrane, rather than binding to a receptor on the surface. Steroid hormones are derived from cholesterol, but there is no such thing as "cholesterol hormones."
Which of the following is a steroid hormone?
Testosterone
Human growth hormone
Insulin
Oxytocin
Explanation
Steroid hormones are created in the gonads and the adrenal cortex. They include testosterone, estrogen, cortisol, aldosterone, and progesterone.
Human growth hormone, oxytocin, and insulin are all peptide hormones, meaning that they are proteins made of amino acids. In contrast, steroid hormones are derived from cholesterol and have distinct ring structures.
What class of hormone must attach to membrane-bound receptors?
Peptide hormones
Steroid hormones
Tyrosine derivative hormones
Cholesterol hormones
Explanation
There are three primary types of hormones: peptide hormones, steroid hormones, and tyrosine derivative hormones. Of the three, peptide hormones are the only polar hormones, so they cannot pass the cell membrane. As a result, they must attach to a membrane-bound receptor in order to elicit a response in the cell.
Tyrosine derivatives and steroid hormones are smaller, nonpolar molecules. This allows them to pass directly through the membrane, rather than binding to a receptor on the surface. Steroid hormones are derived from cholesterol, but there is no such thing as "cholesterol hormones."
Which of the following is a steroid hormone?
Testosterone
Human growth hormone
Insulin
Oxytocin
Explanation
Steroid hormones are created in the gonads and the adrenal cortex. They include testosterone, estrogen, cortisol, aldosterone, and progesterone.
Human growth hormone, oxytocin, and insulin are all peptide hormones, meaning that they are proteins made of amino acids. In contrast, steroid hormones are derived from cholesterol and have distinct ring structures.
What hormone is responsible for lowering blood sugar levels in the body?
Insulin
Glucagon
Oxytocin
Thyroxine
Explanation
Managing blood sugar levels is primarily the responsibility of the pancreatic hormones glucagon and insulin. Glucagon is responsible for raising blood sugar levels while insulin helps reduce the sugar levels.
Oxytocin is a hormone secreted from the posterior pituitary gland; it induces labor and contractions during childbirth. Thyroxine (also known as thyroid hormone or T4) is secreted from the thyroid and helps regulate metabolism.
What hormone is responsible for lowering blood sugar levels in the body?
Insulin
Glucagon
Oxytocin
Thyroxine
Explanation
Managing blood sugar levels is primarily the responsibility of the pancreatic hormones glucagon and insulin. Glucagon is responsible for raising blood sugar levels while insulin helps reduce the sugar levels.
Oxytocin is a hormone secreted from the posterior pituitary gland; it induces labor and contractions during childbirth. Thyroxine (also known as thyroid hormone or T4) is secreted from the thyroid and helps regulate metabolism.
What event in females precedes the egg being released from the follicle?
The luteal surge
Menstruation
Ovulation
Gastrulation
Explanation
Ovulation, or the release of the egg from its follicle, is initiated by a temporary spike in estradiol (estrogen) levels. This positive feedback event is referred to as the luteal surge.
Menstruation follows ovulation. Gastrulation is a phase of development during which the primary germ layers are generated in an embryo, and is not related to the female cycle.
What is the function of the innate immune system?
Attack all pathogens that enter the body
Attack pathogens that the body has been exposed to during previous infection
Attack pathogens that the body is exposed to before birth
Attack pathogens that enter the body through the mouth or nose
Explanation
Your innate immunity is the generalized system responsible for first attacking incoming infectious agents and toxins. Innate means that it is not necessary to have previously seen the pathogen, and the body always has these general defense mechanisms. Macrophages, neutrophils, and basophils are some of the primary cell types of innate immunity.
In contrast, the adaptive immune system is only effective against pathogens that have previously entered the body. A previous infection will result in the body producing antibodies during any later infections. T-cells and B-cells (lymphocytes) are the primary cell types of adaptive immunity.