Diffusion is needed by all forms of life. For example, the Salmonella bacteria below (in pink) are able to sense their environment around them by the diffusion of chemicals across their cell membranes.Complete the sentence below.During diffusion, particles move randomly from where there is a high concentration to areas where there is a __________ concentration of the particle.

Diffusion is the net (overall) movement of particles from an area of high concentration to an area of lower concentration.Question 4Answera.Falseb.True

What is diffusion?The passive movement of particles from a high concentration to a low concentrationThe passive movement of particles from a low concentration to a high concentrationThe active movement of particles using energy from respirationThe passive movement of water though a semi-permeable membrane from an area of high concentration to an area of low concentration2Which of the following factors do not speed up diffusion?Small surface area to volume ratioIncrease in temperatureIncrease in concentration gradientLarge surface area to volume ratio3During ventilation, in which order does air enter the following structures to reach the lungs?Bronchi, bronchiole, trachea, alveoliTrachea, alveoli, bronchi, bronchioleTrachea, bronchi, bronchiole, alveoliBronchi, trachea, bronchiole, alveoli4Which one of the following characteristics would you expect to find in alveoli to make them efficient at gas exchange?Small surface areaRich supply of blood capillariesLong diffusion distanceThick walls5Which two mechanisms are important for maintaining the steep concentration gradients of oxygen and carbon dioxide that are necessary for gas exchange?Respiration and ventilationVentilation and circulationVentilation and excretionRespiration and circulation6During gas exchange:Oxygen moves down a concentration gradient from the air in the alveoli to the bloodOxygen moves down a concentration gradient from the blood to the air in the alveoliOxygen moves up a concentration gradient from the blood to the air in the alveoliOxygen moves up a concentration gradient from the air in the alveoli to the blood

Which of the following is the best definition of diffusion?When particles of a solid, liquid or gas spread out through random movement from an area where there are fewer particles to an area where there are many particles.When particles of a liquid or gas spread out through random movement from an area where there are many particles to an area where there are fewer particles.When particles of a liquid or gas spread out through random movement from an area where there are fewer particles to an area where there are many particles.When particles of a solid, liquid or gas spread out through random movement from an area where there are many particles to an area where there are fewer particles.

1 Assertion (A): Diffusion does not meet high energy requirements of multi-cellular organismsReason (R) : Diffusion is a fast process but occurs at the surface of the body.

Diffusion is:the movement of a substance from a low concentration to a high concentration.the movement of a substance from a high concentration to a low concentration.the movement of a substance from high concentration to a high concentration.the movement of a substance from low concentration to a low concentration.