Вопросы по биологии

What are the products of anaerobic respiration in animals?

• lactate and ATP

• carbon dioxide and ATP

• oxygen, ethanol, and ATP

• carbon dioxide, water, and ATP

What will be the effect of adding a competitive inhibitor of enzyme Z?

• Enzyme Z will be denatured.

• Intermediate 2 will increase in concentration.

• No final product will be produced anymore.

• The reaction rate of enzyme X will slow down.

What is the reason that both DNA strands cannot be replicated continuously?

• There is not enough space to copy both strands.

• DNA polymerase can only act on one strand at a time.

• DNA nucleotides can only be added continuously in the 3´ to 5´ direction.

• DNA nucleotides can only be added continuously in the 5´ to 3´ direction.

What is the difference between embryonic stem cells and tissue stem cells?

• Embryonic stem cells give rise to all types of cell, but tissue stem cells only give rise to
                a limited number of types of cell.

• Embryonic cells are multipotent stem cells, but tissue stem cells are not.

• Tissue stem cells give rise to all types of cell, but embryonic stem cells only give rise to                a limited number of types of cell.

• There are fewer ethical issues with using embryonic stem cells.

Answer explanation

Embryonic stem cells(ESCs): Obtained from embryos   in early   stages of development (inner cell mass of blastocyst)

  Produced by in Vitro fertilization

  - Can divide unlimited number of     times/have  self- renewal

  - Can develop into any type of cell/ are   pluripotent.

  - Subject to many ethical questions.

1.Adult stem cells (ASCs): Obtained from body tissues   of adults. Example bone marrow

  - Are not flexible

  - can specialize into limited range of cells

            ( they are multipotent)

  -less rejected by immune system if it   comes from own patient

The diagram shows some stages in genetic engineering. A gene is cut from human DNA and inserted into a plasmid.

        Which is the vector?

• bacterial DNA

• human gene

• restriction enzymes

• recombinant plasmid

Which of the following is a consequence of inbreeding?

1.      increase in yield

 

2.      increase in size

 

3.      decrease in disease resistance

• A      1 and 2

•      B 1 and 3

• C 3 only

• D     2 and 3

An eyepiece graticule can be calibrated using a stage micrometer.

What is the correct reason why an eyepiece graticule is calibrated?

• An eyepiece graticule can be used to make measurements.

• An eyepiece graticule is magnified by the objective lens.

• An eyepiece graticule magnifies the specimen.

• An eyepiece graticule makes comparisons.

Answer explanation

A measuring device placed in the eyepiece of a microscope and acts as a ruler when you view an object under the microscope

The image is an electron micrograph of a typical eukaryotic cell.What can be concluded about the eukaryotic cell from the electron micrograph?

• It is an animal cell because it does not have a cell wall.

• It is an animal cell because it contains a permanent vacuole.

• It is a plant cell because it contains many chloroplasts.

• It is a plant cell because it contains many lysosomes.

Answer explanation

Animal cells have centrioles, centrosomes (discussed under the cytoskeleton), and lysosomes, whereas plant cells do not. Plant cells have a cell wall, chloroplasts, plasmodesmata, and plastids used for storage, and a large central vacuole, whereas animal cells do not.

 

Which features are found in typical eukaryotes and also in typical bacteria?

• А

• В

• С

• D

Answer explanation

Prokaryotic cells have probably been around for 3.5 billion years - 2.5 billion years longer than eukaryotic cells.

It is thought that eukaryotic cell organelles like mitochondria and chloroplasts are derived from prokaryotic cells that became incorporated inside larger prokaryotic cells. This idea is called endosymbiosis, and is supported by these observations: • organelles contain circular DNA, like bacteria cells. • organelles contain 70S ribosomes, like bacteria cells. • organelles have double membranes, as though a single-membrane cell had been engulfed and surrounded by a larger cell.

Which type of cell will have the highest proportion of its volume taken up with cell structures

bound by a single membrane?

• ciliated epithelial cell

• goblet cell

• red blood cell

• companion cell

Answer explanation

Goblet cells are intestinal mucosal epithelial cells that serve as the primary site for nutrient digestion and mucosal absorption.[2] The primary function of goblet cells is to synthesize and secrete mucus.[1] As the primary secretory cell in the superficial epithelium of large airways, goblet cells secrete mucin