Cell Biology, Human Physiology, and Biological Molecules Flashcards

Comprehensive practice flashcards covering cell organization, movement of substances, biological nutrients, enzymes, nutrition, transport systems, respiration, and excretion based on lecture notes.

What three components make up the protoplasm of a cell?

The nucleus, cytoplasm, and cell membrane.

What is the cell membrane composed of?

A phospholipid bilayer with embedded proteins that controls the movement of substances into and out of the cell.

What carbohydrate makes up the fully permeable cell wall in plant cells?

Cellulose.

Which microscope is required to clearly see the individual structural details of a cell nucleus?

An electron microscope.

What is the primary structural difference between the Rough Endoplasmic Reticulum (RER) and the Smooth Endoplasmic Reticulum (SER)?

The RER has ribosomes attached to its membrane surface, whereas the SER lacks ribosomes and is more tubular.

What are the key functions of the Smooth Endoplasmic Reticulum (SER)?

Synthesizing substances such as fats and steroids, and converting harmful substances into harmless ones through detoxification.

What is the functional difference between free ribosomes in the cytoplasm and attached ribosomes on the RER?

Free ribosomes synthesize proteins used within the cell, while RER-attached ribosomes synthesize proteins transported out of the cell or inserted into membranes.

What functions does the Golgi apparatus perform after receiving proteins and lipids from the endoplasmic reticulum?

It chemically modifies them, sorts and processes them according to function, packages them into secretory vesicles, and releases them outside the cell via exocytosis.

What is the name of the partially permeable membrane that encloses the large central vacuole in a plant cell?

Tonoplast.

Why is the central vacuole in a plant cell considered permanent, unlike animal vacuoles?

It maintains continuous turgor pressure to keep the plant upright, performs ongoing storage of nutrients and wastes, and remains integral to the cell structure throughout its life.

What is cell differentiation?

The process by which a cell becomes specialized for a specific function.

How does the biconcave shape of a red blood cell enhance its primary function?

It increases the surface area to volume ratio for an increased rate of oxygen uptake.

What structural feature deposited on xylem vessel walls prevents them from collapsing?

Lignin.

What is diffusion?

The net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient until equilibrium is reached.

What happens to a plant cell placed in a solution with a lower water potential?

Water leaves the cell by osmosis, causing the cell to become flaccid and the cytoplasm to shrink away from the cell wall in a process called plasmolysis.

What process occurs when an animal red blood cell loses water in a solution of lower water potential?

Crenation, where the cell shrinks and develops surface spikes.

Why does active transport require living cells?

Because active transport moves particles against a concentration gradient, which requires energy released during cellular respiration in the mitochondria.

What reaction joins two simple sugar molecules together with the removal of a water molecule?

Condensation.

Which color precipitate indicates a large amount of reducing sugar during Benedict's test?

A red or brick-red precipitate.

What is the ratio of hydrogen to oxygen atoms in carbohydrates?

2:1.

What is the chemical test for starch and its positive observation?

The iodine test; the solution turns from yellowish-brown to blue-black.

What are the basic building block components of a triglyceride molecule?

One glycerol molecule and three fatty acid molecules.

What are the three chemical groups attached to the central structure of an amino acid?

An amino group ($NH_2$), an acidic/carboxyl group ($COOH$), and a variable side chain (R group).

How do biological enzymes speed up chemical reactions?

By lowering the activation energy required for the reaction to occur.

What happens to an enzyme when exposed to temperatures significantly above its optimum?

Excessive heat causes weak non-covalent bonds to break, changing the shape of the active site so it is no longer complementary to the substrate, causing denaturation.

What are the five main stages involved in animal nutrition?

Ingestion, digestion, absorption, assimilation, and egestion.

What inactive enzyme in the stomach is converted to pepsin by hydrochloric acid?

Pepsinogen.

What is the role of bile in the digestion of fats?

Bile emulsifies large fat droplets into smaller fat droplets, increasing the surface area to volume ratio for faster digestion by lipases.

Which enzyme hydrolyzes peptides into individual amino acids in the small intestine?

Erepsin.

How is the small intestine structurally adapted for efficient nutrient absorption?

It is long and coiled, its inner walls have folds with villi and microvilli to increase surface area to volume ratio, and it has a thin one-cell thick epithelium with rich capillary networks.

What is deamination and in which organ does it occur?

Deamination is the removal of the toxic amino group from excess amino acids to form urea, occurring in the liver.

What is the normal blood glucose concentration maintained by the liver?

70 to 90 mg of glucose per $100\,cm^3$ of blood.

What actions are triggered by insulin when blood glucose levels rise above normal?

Insulin makes cell membranes more permeable to glucose and stimulates the liver and muscle cells to convert excess glucose into glycogen.

Which enzyme breaks down alcohol in liver cells during detoxification?

Alcohol dehydrogenase.

What is the main function of B-lymphocytes in the human immune response?

They produce specific antibodies that cause bacteria to clump together (agglutination), neutralise toxins, and make pathogens easier for phagocytes to engulf.

What conversion occurs during blood clotting to form a scab?

Enzymes catalyze the conversion of soluble protein fibrinogen into insoluble fibrin threads that entangle blood cells.

Which main blood vessel carries oxygenated blood from the lungs back to the left atrium?

Pulmonary vein.

What causes the heart sounds 'Lub' and 'Dub' during the cardiac cycle?

'Lub' is caused by the closure of the tricuspid and bicuspid valves during ventricular systole; 'Dub' is caused by the closure of the semi-lunar valves during ventricular diastole.

What chemical equation represents aerobic respiration?

$$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$$

What substance accumulates in muscles during anaerobic respiration, creating an oxygen debt?

Lactic acid.

Why does carbon monoxide in tobacco smoke cause severe oxygen deprivation in tissues?

Carbon monoxide binds 200 times more readily to haemoglobin than oxygen to form carboxyhaemoglobin, drastically reducing oxygen transport.

What structural component prevents the trachea from collapsing during pressure changes?

C-shaped rings of cartilage.

What two processes are responsible for urine formation inside the nephron?

Ultrafiltration at the glomerulus and selective reabsorption along the tubule.

What is the role of Antidiuretic Hormone (ADH) in osmoregulation?

ADH increases water reabsorption at the collecting ducts of the nephrons back into blood plasma, concentrating the urine and maintaining blood water potential.