B2.3 HL only

Question 1

diffusion

Answer 1

the movement of particles from higher to lower concentrations

Question 2

facilitated diffusion

Answer 2

a type of passive transport where molecules move across a cell membrane with the help of specific proteins, called carrier proteins or channel proteins, without requiring the cell to expend energy

Question 3

Biconcave shape

Answer 3

a structure, typically a disc or lens, that is concave (curved inward) on both sides.This shape is most famously known for its appearance in red blood cells (erythrocytes), which are flattened with a dip on both faces, maximizing their surface area for oxygen absorption

Question 4

microvilli

Answer 4

tiny, finger-like projections extending from the cell membrane of certain cells, primarily epithelial cells

Question 5

Proximal convoluted tubule cells (PCT cells)

Answer 5

specialized epithelial cells that line the first part of the nephron, a functional unit of the kidney

Question 6

nephron

Answer 6

the fundamental functional unit of the kidney, responsible for filtering blood and producing urine

Question 7

Tight junctions

Answer 7

specialized structures that seal the spaces between adjacent cells, creating a barrier that regulates the passage of molecules and ions between them

Question 8

alveoli

Answer 8

the tiny, microscopic air sacs in the lungs where the exchange of oxygen and carbon dioxide between the air and the blood occurs

Question 9

Type I pneumocytes

Answer 9

thin, flattened cells that line the inner surface of the alveoli in the lungs

Question 10

Type II pneumocytes

Answer 10

specialized cells lining the alveoli (tiny air sacs) in the lungs.They are cuboidal in shape and responsible for producing and secreting pulmonary surfactant, a substance that reduces surface tension within the alveoli

Question 11

pulmonary surfactant

Answer 11

a complex mixture of lipids and proteins produced by type II alveolar cells in the lungs.Its primary function is to reduce surface tension at the air-liquid interface of the alveoli, preventing their collapse during exhalation and facilitating lung inflation

Question 12

Smooth muscle

Answer 12

a type of muscle tissue characterized by involuntary, non-striated contractions, and is found throughout the body in the walls of internal organs like the stomach and intestines, as well as in blood vessels

Question 13

Striated muscle

Answer 13

a type of muscle tissue characterized by its striped or striated appearance due to the organized arrangement of contractile proteins.This organization is based on repeating functional units called sarcomeres, which contain thick and thin filaments of proteins like myosin and actin

Question 14

sarcolemma

Answer 14

the cell membrane that surrounds each muscle fiber

Question 15

Multinucleated

Answer 15

a cell or structure that contains more than one nucleus.These nuclei are typically present within the same cell’s cytoplasm, sharing a common cellular environment

Question 16

Cardiac muscle

Answer 16

one of the three types of muscle tissue in the human body, along with skeletal and smooth muscle

Question 17

intercalated discs

Answer 17

specialized junctions between cardiac muscle cells (cardiomyocytes) that facilitate both electrical and mechanical coupling, enabling synchronized heart muscle contraction

Question 18

Gametes

Answer 18

reproductive cells, or sex cells, that combine during sexual reproduction to form a new organism

Question 19

sexual reproduction

Answer 19

a mode of reproduction that involves the fusion of male and female sex cells (gametes) to create offspring

Question 20

acrosome

Answer 20

a specialized organelle, a cap-like structure, found at the tip of sperm cells (spermatozoa)

Question 21

zona pellucida

Answer 21

a thick, acellular extracellular matrix that surrounds all mammalian oocytes, unfertilized eggs, and preimplantation embryos