Unit 1 aos 2

Question 1

DIGESTION- oral cavity

Answer 1

The beginning of the digestive system and the site of ingestion. Teeth mechanically break food into small pieces, digestive amylase enzymes in saliva start the breakdown of carbohydrates, and lipase enzymes in the mouth start the breakdown of fats. The chewing of food occurs here. The pH of the mouth ranges from 6–8.

Question 2

DIGESTION- Salivary glands

Answer 2

Glands that produce and release saliva into the
mouth and oesophagus.

Question 3

DIGESTION- Oesophagus

Answer 3

A hollow tube connecting the oral cavity to the
stomach which food travels down after being
swallowed. Saliva continues to mix with the food.
The movement of the food is aided by waves of
muscular contractions of the tube, known as
peristalsis.

Question 4

DIGESTION- stomach

Answer 4

A temporary storage tank where food is mixed by muscular movements known as churning.
Protease enzymes are secreted by the stomach
and begin the digestion of protein materials.
Digestive juices are released by the stomach
membrane, which creates an acidic environment of
pH 1–3. Peristalsis of the stomach muscles helps push food along to the small intestine. Partially digested food that leaves the stomach is known as chyme.

Enzyme: Pepsin (activated by hydrochloric acid).
Compound digested: Proteins into polypeptides and smaller peptides.

Question 5

DIGESTION- liver

Answer 5

The liver is the site of bile production. Bile is
important in the physical breakdown of fats –
smaller fat particles are then more readily
broken down by lipase enzymes. The liver also
has important roles in regulating metabolism,
toxin removal, and processing nutrients.
The liver stores excess glucose in the form of
glycogen, which can be converted back to
glucose when needed for energy.

Question 6

DIGESTION- gallbladder

Answer 6

After being produced in the liver, bile is stored
and further concentrated in the gallbladder
before it is released into the small intestine

Question 7

DIGESTION- pancreas

Answer 7

Digestive enzymes are produced in the
pancreas and are released when food
reaches the first part of the small intestine.
The pancreas also regulates blood sugar levels
and is responsible for secreting bicarbonate,
which neutralises acids in chyme.

Amylase: Continues digestion of starch into maltose.
Trypsin and chymotrypsin: Continue digestion of proteins into smaller peptides.
Lipase: Breaks down lipids (triglycerides) into fatty acids and glycerol.

Question 8

DIGESTION- small intestine

Answer 8

The main function of the small intestine (divided into three sections: the duodenum, the jejunum, and the ileum) is to absorb nutrients from food. Enzymes produced in the small intestine, enzymes from the pancreas, and bile from the gallbladder aid the breakdown of food in chyme. Continued breakdown of carbohydrates and proteins occurs in the small intestine, as well as the majority of fat breakdown. The cells lining the small intestine absorb nutrients and certain waste products of digestion and deliver them to the circulatory system.

Question 9

DIGESTION- large intestine

Answer 9

The final absorption of water, vitamins, and minerals occurs in the large intestine which is made up of the cecum, colon, and rectum. The junction between the small and large intestines is called the cecum. As water is reabsorbed from undigested food, food becomes more solid and compact, eventually turning i ntofaeces ready for egestion. The large intestine has a large number of bacteria.

Question 10

DIGESTION- rectum

Answer 10

Final area of the large intestine that stores faeces for elimination.

Question 11

DIGESTION - anus

Answer 11

The end of the digestive tract where faeces are
expelled from the body

Question 12

DIGESTION- define ingestion:

Answer 12

Ingestion is the process of taking food into the body through the mouth.
It is the first step in the digestive process

Question 13

DIGESTION- define digestion

Answer 13

Digestion is the process of breaking down food into smaller, absorbable molecules, using mechanical and chemical means.

Question 14

DIGESTION- define absorption

Answer 14

Absorption is the process by which the products of digestion are taken up from the digestive tract into the body’s internal environment

Question 15

DIGESTION- define egestion

Answer 15

Elimination/egestion – the final step is the elimination of undigested food content that has travelled along the digestive tract and has not been absorbed. Undigested food is eliminated from the body as faeces.

Question 16

DIGESTION- chemical vs mechanical

Answer 16

physical/mechanical digestion:
Physical digestion describes the processes whereby the mechanical movement of organs and tissues causes this breakdown of food into smaller pieces. These movements include chewing, muscle contractions, and the stirring of food and digestive juices by muscle movements.

chemical digestion:
Chemical digestion – food pieces undergo chemical digestion by enzymes and stomach acid, producing smaller molecules that are capable of being absorbed. Most digestive
enzymes split food molecules in hydrolysis reactions, by adding water molecules.The three major types of digestive enzymes are amylases (which act on carbohydrates),
proteases (proteins), and lipases (lipids).

Question 17

what is the excretory system?

Answer 17

The purpose of the excretory system is to remove excess and unwanted substances from the body and to maintain a stable internal environment

Question 18

EXCRETORY- kidney structure and function

Answer 18

The kidneys filter blood to remove metabolic wastes like urea, uric acid, creatinine, excess water, and salts, helping to maintain homeostasis.

Blood enters the kidney via the renal artery, which branches into smaller capillaries and delivers blood to nephrons.

-In humans, the kidneys are two bean-shaped organs located in the upper back on either side of the spinal column.
-Their main roles are to filter blood, reabsorb useful substances from the filtrate, and secrete unwanted materials.
-Blood is delivered to the kidneys via the renal arteries, which supply up to 25% of the body’s blood volume at any one time.
-The unfiltered blood contains nitrogenous wastes such as urea, uric acid, and creatinine. Within the kidneys, the renal arteries branch into smaller capillaries that supply blood to millions of nephrons — the functional units of the kidney.
-Each nephron receives blood through afferent capillaries and drains it through efferent capillaries, enabling the processes of filtration, reabsorption, and secretion to occur.

Question 19

EXCRETORY- what is the urinary tract?

Answer 19

The collection of interconnected organs involved in the production and excretion of urine
- kidneys: filter blood + produce urine
-ureters: transport
- bladder: stores urine
- urethra: transports urine bladder to external environment

Question 20

EXCRETORY- layers of the kidney

Answer 20

Renal capsule:
-Outermost layer.
-A tough, fibrous membrane that protects the kidney from trauma and infection.
-Helps maintain the shape and structure of the kidney.

Renal cortex:
Just beneath the capsule.
Contains:
Glomeruli
Bowman’s capsules
Proximal and distal convoluted tubules
This is where filtration of blood begins.
Appears granular due to the presence of renal corpuscles.

Renal medulla:
Inner region of the kidney, deeper than the cortex.
Made up of renal pyramids.
Contains:
Loops of Henle
Collecting ducts
Plays a major role in concentrating urine.

Question 21

EXCRETORY- nephron tube

Answer 21

1. Filtration (in the renal corpuscle)
   Occurs in the glomerulus and Bowman’s capsule (in the renal cortex).

High-pressure blood forces water, urea, salts, glucose, and other small molecules out of the blood into the nephron.

Blood cells and proteins remain in the blood (too large to pass through).

2. Reabsorption (mainly in proximal tubule and loop of Henle)
   Useful substances like glucose, amino acids, water, and some ions are reabsorbed back into surrounding capillaries.

Helps the body retain essential materials.

3. Secretion (mainly in distal tubule)
   Additional wastes (e.g. hydrogen ions, toxins, drugs) are actively transported from the blood into the nephron.
4. Excretion (in collecting duct → ureter)
   The remaining fluid, now called urine, contains urea, salts, and water.

It drains into the renal pelvis, down the ureter, and into the bladder for elimination.

Question 22

EXCRETORY: How are the different parts of the nephron adapted to perform the tasks they do?

Answer 22

The nephron is adapted to efficiently filter blood and form urine through its specialised structures. The glomerulus has thin, high-pressure capillaries that allow small molecules to be filtered into Bowman’s capsule. The proximal convoluted tubule has microvilli and many mitochondria to increase surface area and energy for reabsorbing useful substances. The loop of Henle creates a salt gradient in the medulla to concentrate urine, with different permeabilities in its descending and ascending limbs. The distal tubule fine-tunes ion and pH balance, and the collecting duct, controlled by ADH, reabsorbs water to adjust urine concentration.

Question 23

EXCRETORY- ADH hormone

Answer 23

Antidiuretic hormone (ADH), also known as vasopressin, is a hormone produced by the hypothalamus and released from the posterior pituitary gland. It plays a key role in maintaining water balance in the body by increasing the permeability of the collecting ducts in the nephrons. When the body is dehydrated or blood osmolarity is high, ADH is released, allowing more water to be reabsorbed from the filtrate back into the bloodstream. This results in a smaller volume of more concentrated urine and helps restore blood water levels, contributing to homeostasis. ADH release is triggered by osmoreceptors in the hypothalamus that detect changes in blood solute concentration.

Question 24

ENDOCRINE - what is the endocrine system?

Answer 24

The endocrine system is a group of glands that release hormones into the bloodstream to regulate body functions like growth, metabolism, and reproduction.

Question 25

ENDOCRINE- What hormones are involved in regulating, blood glucose and water balance?

Answer 25

Insulin is released by the pancreas when blood glucose is high (like after eating). It tells cells to absorb glucose from the blood, lowering blood sugar levels. Glucagon is released by the pancreas when blood glucose is low (like between meals). It signals the liver to break down stored glycogen into glucose and release it into the blood, raising blood sugar levels. ADH is released by the pituitary gland when the body is dehydrated. It tells the kidneys to save water by concentrating the urine, helping maintain the body’s water balance.

Question 26

ENDOCRINE- what organs play a role in this process?

Answer 26

Pancreas: It acts as both an endocrine and exocrine gland. In blood glucose regulation, the pancreas releases insulin from beta cells when blood sugar is high and glucagon from alpha cells when blood sugar is low, helping maintain stable glucose levels. Liver: The liver stores excess glucose as glycogen. When glucagon signals it, the liver breaks down glycogen into glucose and releases it into the bloodstream to increase blood sugar levels. Kidneys: They filter blood and control how much water is lost as urine. When ADH is present, the kidneys’ collecting ducts become more permeable to water, allowing more water to be reabsorbed back into the bloodstream, reducing urine volume and conserving water. Pituitary gland: The posterior pituitary releases ADH in response to signals from the hypothalamus when the body is dehydrated or blood osmolarity is high. This hormone helps prevent dehydration by increasing water reabsorption in the kidneys.

Question 27

PLANT SYSTEM- Name and describe the tissues which vascular plants have that allows them to transport dissolved sugars and water

Answer 27

Xylem: Made up of vessels and tracheids—these are long, hollow, dead cells that join end to end to form tubes. Water and minerals are pulled up through these tubes by transpiration (evaporation of water from leaves). The rigid walls also help support the plant. Phloem: Consists mainly of sieve tube elements and companion cells. Sieve tubes transport dissolved sugars (mainly sucrose) from the leaves (where sugars are made during photosynthesis) to growing parts and storage tissues. Companion cells help load sugars into sieve tubes and keep them alive.

Question 28

PLANT SYSTEM- How do plants regulate water loss?

Answer 28

Stomata are tiny pores mostly on the underside of leaves. Each stoma is flanked by two guard cells that control its opening and closing. When guard cells take up water, they swell and curve, opening the stomata. This allows water vapor to escape (transpiration) and carbon dioxide to enter for photosynthesis. When the plant is dehydrated or under stress (like drought or high temperatures), the guard cells lose water, become flaccid, and close the stomata, reducing water loss. Plants also regulate water loss by producing a waxy cuticle on leaf surfaces that minimizes water evaporation. Additionally, some plants have adaptations like fewer stomata, sunken stomata, or hairs around stomata to reduce water loss in dry environments.

Question 29

stimulus response model

Answer 29

Stimulus: A change in the environment that is detected (e.g., a rise in blood glucose). Receptor: Detects the stimulus (e.g., cells in the pancreas detecting blood glucose levels). Modulator: Processes the information and coordinates a response (e.g., the brain or endocrine glands like the pancreas). Effector: Carries out the response (e.g., liver or muscle cells absorbing glucose). Response: The action taken to counteract or adjust to the stimulus (e.g., blood glucose levels decrease).