Define the term chromosome.
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Define the term chromosome.
Chromosomes are structures formed by the coiling of DNA double helices in the nucleus of a cell, visible during cell division, and containing genetic information in the form of genes.
True or False?
Each chromosome carries a large number of genes.
True.
Each chromosome carries many genes which code for many different types of protein.
How many chromosomes do human body cells contain?
Human body cells contain 23 pairs of chromosomes, totalling 46 chromosomes in diploid cells (often represented as 2n).
Why are chromosomes found in pairs in human body cells?
Chromosomes are found in pairs called homologous pairs. One chromosome in each pair is inherited from each parent.
They carry corresponding genes, although they may have different alleles for each gene.
How is the chromosome number in the gametes different to that of body cells?
Gametes (sperm and egg cells) contain the haploid number of chromosomes (n), which is half the diploid number found in body cells.
True or False?
Chromosome numbers are consistent across all organisms.
False.
The number of chromosomes differs between species.
True or False?
Chromosomes are only visible during cell division.
True.
Chromosomes condense and become visible during cell division (like mitosis or meiosis) when the DNA coils tightly to form distinct structures.
Define the term mitosis.
Mitosis is nuclear division that results in the production of genetically identical cells. It is used for growth, repair, and asexual reproduction.
True or False?
Mitosis results in genetically diverse cells.
False.
Mitosis results in genetically identical cells.
What happens to chromosomes before mitosis?
Before mitosis each chromosome replicates, producing two identical copies of each chromosome; one for each of the two daughter cells.
Why is mitosis important in the body?
Mitosis is important in the body to produce new cells for growth, repair of damaged tissues, and the replacement of cells.
What is the outcome of a mitotic division?
A mitotic division produces two genetically identical daughter cells. The daughter cells are genetically identical to each other and to the parent cell.
What cells are not produced by mitosis in animals and plants?
The gametes (i.e. sperm, egg cells, pollen and ovules) are not produced by mitosis, instead they are produced by meiosis.
How many chromosomes are present in a human cell produced by mitosis?
Human cells produced by mitosis contain 23 pairs of, or 46, chromosomes.
True or False?
Mitosis is another name for the cell cycle.
False.
Mitosis is a part of the cell cycle. The majority of the cell cycle is spent in the stage when the cell grows and DNA replicates.
Name the three stages of the cell cycle.
The cell cycle is made up of
cell growth, DNA replication and organelle replication
mitosis (division of the nucleus)
cytokinesis (splitting of the cytoplasm)
True or False?
Ribosome numbers increase in cells before mitosis occurs.
True.
In order for cell division to occur successfully, the subcellular structures must replicated. This includes ribosomes and other organelles such as mitochondria.
Define the term stem cell.
A stem cell is an undifferentiated cell capable of giving rise to many more cells of the same type and from which other cells can arise from differentiation
True or False?
Embryonic stem cells can differentiate to produce most cell types.
True.
Embryonic stem cells can differentiate into most, or in some cases all, cell types. This enables them to form the tissues and organs needed during development.
How can stem cells be used to treat diseases such as diabetes?
Stem cells could potentially treat diseases such as diabetes by replacing damaged/unhealthy cells with healthy stem cells, which can continually divide to form more healthy cells.
True or False?
There is risk of infection when transferring lab-cultured stem cells into a patient.
True.
Stem cells cultured in a lab can become infected. Infection can then be passed to patients during therapy.
What is the potential benefit of being able to use a patient's own stem cells in medical treatment?
A potential benefit of being able to use a patient's own stem cells in medical treatment is that stem cells from the same patient would not be rejected by the patient's immune system.
True or False?
There are ethical issues associated with the use of embryonic stem cells in medicine.
True.
Many have ethical concerns around the use of embryonic stem cells in medicine. These concerns are related to whether or not embryos should have human rights. Concerns include:
Destruction of embryos
Embryos cannot give consent
Embryos are treated as a commodity
True or False?
Adult stem cells have a limited capacity to differentiate.
True.
Adult stem cells have a limited ability to differentiate; they can only give rise to a few cell types.
Name the tissue type found in plants where stem cells are located.
Stem cells in plants are found in meristem tissue in the growing roots and shoots.
What is the location in the human body of the stem cells that differentiate to form red blood cells?
Red blood cells differentiate from stem cells found in the bone marrow.
What are the key benefits of stem cell use in crop farming?
Farmers use stem cells from the meristems of crop plants to quickly and economically produce large numbers of crop plants with special features e.g. disease resistance.