6.3 Defence Against Infectious diseases (IB Biology)

What is thought of as the primary defenses against pathogens in the human body?

• Lymphocytes and phagocytes

• Antibodies and lymphocytes

• The skin and mucous membranes

• The circulatory system

If the skin is broken then a blood clot forms to seal this cut.

What is the first step in the process of blood clotting?

• Fibrinogen turns into fibrin

• Platelets release clotting factors

• Fibrinogen is converted into thrombin

• Thrombin is converted into prothrombin

What is the effect which thrombin has on the process of blood clotting?

• Fibrinogen is converted to fibrin

• Prothrombin is converted to thrombin

• Platelets are caused to release clotting factors.

• Clotting factors are taken up by red blood cells.

Which type of blood cells are capable of ingesting pathogens?

• Erythrocytes

• Antibodies

• Lymphocyte cells

• Phagocyte cells

Anitigens on pathogens which have got into the human body can lead to the development of specific immunity.

That is an immunity which responds only to this antigen.

Which of the following cells causes the specific immunity?

• Erythrocytes

• Macrophages

• Lymphocytes

• Phagocytes

Why do antibiotics have little or no effect on human cells, yet they can cause the death of bacteria?

• Antibiotics block prokaryote cell processes, but not the processes in eukaryote cells.

• Antibiotics can only affect cells below a certain size.

• Human cells have a protective plasma membrane which prokaryote cells don't have.

• Antibiotics are made of proteins which cannot pass through the plasma membrane.

There are limits to the effectiveness of antibiotics.

Why is this?

• Viruses are not affected because they have no metabolism, and some bacteria have evolved resistance.

• Bacteria are not affected by antibiotics, only viruses.

• Only one species of bacteria is affected by a single antibiotic.

• Only some types of virus and bacteria are affected by antibiotics, because of the evolution of resistance.

Tags

NGSS.HS-LS4-2

Which of the following best describes the effect of HIV on the immune system.

• HIV infection causes a reduction in the number of active blood cells resulting in a high fever.

• HIV reduces the number of active lymphocytes limiting the body's ability to produce antibodies.

• HIV reduces the number of active erythrocytes limiting the production of antibodies.

• HIV reduces the number of phagocytes which in turn limits the production of antibodies.

When activated by the presence of a pathogen some lymphocytes produce antibodies and other lymphocytes act as memory cells.

Which of the following best describes the role of memory cells in the immune system?

• They store antigens from the pathogen for lymphocytes to use as a template for antibodies in the future.

• They remember the antigen on the pathogen and tell the lymphocytes how to respond if it is re-encountered.

• They quickly clone to form a group of phagocytes if the pathogen is re-encountered.

• They quickly clone to form a group of plasma cells if the pathogen is re-encountered.

Which of the following is the best explanation of the likely consequences of a blood clot forming in a coronary artery?

• Part of the heart receives a slower supply of blood, and contractions of the heart become irregular.

• The blood is prevented from getting to the cardiac muscle and it stops contraction, the heart stops beating.

• The blood stops flowing into the heart and this prevents the flow of blood around the body.

• The blood clot moves from the coronary artery to the brain causing a stroke.