IGCSE Biology: Cells, Transport, Enzymes, and Nutrition

Comprehensive fill-in-the-blank practice flashcards covering cell biology, organelles, microscopy, classification of living organisms, diffusion, osmosis, active transport, enzyme kinetics, biological molecules, and the human digestive system.

The ability of an organism to maintain a steady and constant internal environment, such as controlling body temperature and blood glucose levels, is known as __________.

homeostasis

During aerobic respiration, energy released from the breakdown of glucose is stored when ADP and phosphate combine to form __________.

ATP

The removal of toxic metabolic waste products or substances in excess of requirements from the body is called excretion, whereas the removal of undigested food as faeces through the anus is termed __________.

egestion

Non-membranous organelles found only in animal cells that assemble spindle fibres during cell division are called __________.

centrioles

In animal cells, membrane-bound vesicles that contain digestive enzymes to break down pathogens during phagocytosis and digest worn-out organelles are called __________.

lysosomes

In the mitochondrion, the folded inner membrane that increases surface area for aerobic respiration and ATP production is known as the __________.

cristae

The magnification of a biological specimen under a microscope is calculated as: $\text{Magnification} = \frac{\text{Image size}}{\text{\_\_\_\_\_\_\_\_\_\_}}$.

Actual size

To convert a biological measurement from centimeters ($\text{cm}$) directly to micrometers ($\mu\text{m}$), you multiply the value by __________.

$$10\,000$$

The method of nutrition seen in fungi, where extracellular digestive enzymes are secreted onto decaying matter and the soluble digested products are absorbed, is described as __________.

saprotrophic

Unlike plant cell walls made of cellulose or fungal cell walls made of chitin, bacterial cell walls are composed of a complex of sugars and proteins called __________.

murein

In the classification of bacterial morphology, rod-shaped bacteria are called bacilli, whereas spherical bacteria are known as __________.

cocci

A virus particle lacks a cellular structure and consists of genetic material (DNA or RNA) enclosed within a protective __________.

protein coat

In the respiratory lining, sticky mucus that traps bacteria and dust particles is produced and secreted by __________.

goblet cells

The specialized cap-like structure at the front of a sperm cell's head containing digestive enzymes to penetrate the jelly coat of an egg is the __________.

acrosome

Mature mammalian red blood cells lack a nucleus and have a __________ shape to maximize the surface area for diffusion of oxygen.

biconcave

Unspecialized cells found in the early stages of embryo development that have the potential to differentiate into any cell type in the body are called __________ stem cells.

embryonic

In the binomial naming system, an organism's scientific name consists of two parts: the first indicates the __________ with a capital letter, and the second indicates the species.

genus

Arthropods characterized by having three pairs of legs, a body divided into head, thorax, and abdomen, and one pair of antennae belong to the class __________.

Insects

Mammals are distinct from other vertebrate classes because females possess mammary glands to produce milk, bodies are covered with fur, and their ears feature an external flap called a __________.

pinna

Ferns do not produce flowers; instead, they reproduce by spores produced in structures called __________ located on the undersides of their fronds.

sporangium

Diffusion is defined as the net movement of particles from a region of higher concentration to a region of lower concentration down a __________.

concentration gradient

Large multicellular organisms require specialized circulatory systems because their __________ is too small to supply internal cells by simple diffusion alone.

surface area to volume ratio

Osmosis is the net movement of water molecules from a dilute solution (higher water potential) to a concentrated solution (lower water potential) across a __________.

partially permeable membrane

When a plant cell is placed in a concentrated sucrose solution, it loses water by osmosis until the cell membrane shrinks away from the cell wall, becoming __________.

plasmolysed

Unlike plant cells protected by a rigid cell wall, animal cells placed in pure water take in water by osmosis, swell, and __________.

burst (lyse)

In a potato cylinder osmosis investigation, the sucrose concentration where there is zero percentage change in mass represents the __________ concentration.

isotonic

Active transport is the movement of substances against a concentration gradient across a membrane through carrier proteins, requiring metabolic energy in the form of __________.

ATP

Enzymes are biological catalysts that accelerate chemical reactions by lowering the __________.

activation energy

Above an enzyme's optimum temperature, the bonds maintaining the three-dimensional shape of the active site break, causing the enzyme to become irreversibly __________.

denatured

When lipase digests lipids present in milk, the pH of the mixture decreases because the reaction products are glycerol and acidic __________.

fatty acids

In an amylase-starch spotting tile investigation, starch breakdown is considered complete when the added iodine solution remains __________.

yellow (or yellowish-brown)

In animals, surplus carbohydrates are stored inside liver and muscle cells in the form of the polysaccharide __________.

glycogen

A lipid (triglyceride) molecule is synthesized from one molecule of __________ chemically bonded to three fatty acid molecules.

glycerol

To test a food sample for protein, Biuret reagent is added; a positive result produces a __________ colour.

purple (or violet)

When testing a food solution for reducing sugars, adding Benedict's solution and heating in a water bath causes a colour change from blue to a __________ precipitate.

brick red

In the emulsion test for lipids, dissolving the food in ethanol and then adding cold water produces a positive result seen as a __________.

milky white emulsion

Vitamin C concentration can be measured by adding food juice drop by drop to the blue dye __________, which turns colourless upon reduction.

DCPIP

A deficiency of vitamin D or inadequate exposure of skin to sunlight impairs calcium uptake and causes __________ in growing children.

rickets

Vitamin C is essential for sticking together cells lining internal body surfaces; its deficiency leads to __________.

scurvy

A deficiency in the mineral ion iron reduces haemoglobin synthesis in red blood cells, leading to __________.

anaemia

Roughage consists mainly of indigestible plant cellulose that adds bulk to feces and stimulates digestive muscles to move food by __________.

peristalsis

The calculated energy content of a food sample obtained from simple calorimeter burning is typically lower than the value on the nutrition label because heat is lost to surroundings and the sample is __________.

not completely burnt

During swallowing, food is prevented from entering the trachea by a cartilaginous flap called the __________.

epiglottis

In gastric juice, hydrochloric acid kills ingested microorganisms and provides an acidic optimum pH that converts inactive pepsinogen into the active protease __________.

pepsin

Bile salts produced by the liver and stored in the gall bladder do not chemically digest fats, but instead __________ large fat globules into smaller droplets.

emulsify

Inside an intestinal villus, amino acids and glucose are absorbed into blood capillaries, whereas digested fatty acids, glycerol, and fat-soluble vitamins enter the __________.

lacteal

In a tooth, the outer hard calcified cap is the enamel, while the layer beneath it that is less hard and dissolves faster in bacterial acid is the __________.

dentine

Excess amino acids cannot be stored in the body and undergo deamination in the liver, where the nitrogen-containing amino group is converted into __________.

urea