M2 - Organisation of living things

Question 1

Define unicellular

Answer 1

One type of cell that is mostly prokaryotic. The cell carries out all functions to sustain life meaning it has a short lifespan. They reproduce asexually with the whole organism involved in reproduction.

Question 2

Define colonial

Answer 2

Many cells of individual animals which work together to keep a colony alive. They have a longer lifespan as energy is shared amongst colony. Asexual, clonal reproduction with specific zooids for reproduction. Cells can live independently.

Question 3

Define multicellular

Answer 3

Many specialized, eukaryotic cells with specific functions required by the organism. They have a long lifespan with mostly sexual reproduction which gametes are responsible for.

Question 4

What is cell specialisation?

Answer 4

The particular function that a cell evolves to form

Question 5

What is cell differentiation?

Answer 5

The process of an unspecialised cell becoming specialised

Question 6

What is a stem cell and what is the relationship of structure to function?

Answer 6

A stem cell is an un undifferentiated cell with the potential of becoming any body cell. Stem cells develop structures and features directly linked to their function. The location of the cell determinds the type of cell formed.
For example red blood cells have no nucleus and is a flat disc shape to carry oxygen
Root hair cells are long and flat to increase SA:V ration for absorption

Question 7

What are the 4 kinds of plant tissues?

Answer 7

Meristematic, vascular, dermal, plant

Question 8

What are the roles of the 3 plant organs?

Answer 8

Root: absorption of water and minerals from the soil
Stem: Transports water and minerals from the roots to the leaves
Leaves: Site of photosynthesis and allows gas exchange

Question 9

Describe the plant organ systems

Answer 9

The root system is below the ground, responsible for absorbing water and nutrients from the soil to the plant.
The shoot system is above the ground, responsible for transporting substances and gases around the plant as well as photosynethesis.

Question 10

What are the 4 types of animal tissues?

Answer 10

Muscular, nervous, epithelial, connective

Question 11

What are the 3 kind of muscle tissues?

Answer 11

Cardiac, skeletal and smooth

Question 12

What are organs and organ systems made up of?

Answer 12

Organs are made up of tissues grouped together to perform a function while organ systems are organs grouped together to perform a bodily function

Question 13

What is the organisational hierarchy of living things? provide an example

Answer 13

organelle -> cell -> tissue -> organ -> organ system -> organism

nucleus -> myocytes -> muscular tissue -> heart -> cardiovascular system -> human

Question 14

Name six cells in a leaf required for gas exchange

Answer 14

Stomate pore, guard cell, cuticle, epidermis, palisade mesophyll, spongy mesophyll

Question 15

Name 3 imaging technologies used to view the process of photosynthesis

Answer 15

MRI: creates 3D images
PET: details of transport function
NT: shows plant root system and water distribution

Question 16

How is technology used to trace the products of photosynthesis?

Answer 16

Radioisotopes emit radiation which is detected to show a pathway of molecules.
Oxygen-18 shows oxygen comes from water
Carbon-14 show glucose come from carbon

Question 17

How does gas exchange occur in plants?

Answer 17

Guard cells fill with water and become turgid, making them curve outward and open the pore. Carbon enters the stomata and diffuses into the spongy or palisade mesophyll to undergo photosynthesis. Oxygen and water created exits the open stomata and the water loss from guard cells close the pore

Question 18

What is the role of the xylem?

Answer 18

The xylem transports water and mineral ions from roots to leaves in one direction. It contains tracheids and xylem vessel which are dead cells as well as lignin which reinforces and strengthens the walls.

Question 19

Explain the TCT theory

Answer 19

The Transpiration-Cohesion-Tension theory is a process explaining the transportation of water through xylem in plants. Transpiration is the evaporation and diffusion of water from the stomata as vapor. The attraction of water molecules to each other is known as cohesion, while the attraction of water to the xylem wall is adhesion. The tension creates a transpiration stream which pulls the water up the xylem walls from the roots to leaves. Water then enters the roots via osmosis and is pulled up the transpiration stream due to the root pressure.

Question 20

What is the role of the phloem?

Answer 20

The phloem transports sugars dissolved in water both up and down the plant. The tube is made up of sieve tubes which contain sieve plate that allows rapid flow of sugars as well as companion cells which provide ATP and nutrients for active transport. It is made up of living cells.

Question 21

What is the Source-Sink Theory

Answer 21

A theory explaining translocation- the movement of sucrose from leaves to around the plant though the phloem. The leaves are the source of sucrose production where glucose is converted to sucrose and actively pumped into the phloem tube. Water enters the phloem via osmosis creating a high pressure area. The dilute solution moves down the pressure gradient to an area of low pressure, the stem, roots, buds (sink). Sucrose is actively removed from phloem tissue and water returns to xylem via osmosis, creating an are of low pressure.

Question 22

How do Heterotrophs obtain nutrients? Explain the process

Answer 22

Heterotrophs gain nutrients through the digestive system where food is broken down and released into the blood for growth and repair. Food first enters the mouth where it is mechanically broken down from the teeth and chemically broken down from amylase (saliva). The bolus passes the oesophagus into the stomach where it is further broken down. Chyme enter the duodenum where the pancreas and liver secretes enzymes to aid break down. The small intestine is the main site of absorption through villi followed by the large intestine where remaining waste is turned into feces and passed though the rectum and anus.

Question 23

Compare and contrast mechanical and chemical digestion.

Answer 23

Both methods are processes that occur during digestion to break down foods for absorption. Mechanical digestion occurs in the mouth from teeth which chew and rip food apart as well as the stomach during churning to increase SA:V ratio for chemical digestion. Chemical digestion on the other hand involves the secretion of digestive enzymes including amylase and lipase which breakdown complex molecules into simple molecules.

Question 24

How do humans, fish and insects obtain gases?

Answer 24

Humans obtain oxygen through their respiratory system which connects with the cardiovascular system. Air enters the nose and mouth and passes the pharynx, larynx and down the trachea. The trachea branches into two bronchi in the right and left lung which continues branching into bronchioles to alveoli. Alveoli are one cell thick and lined with capillaries, allowing CO2 and O2 to be exchanged via diffusion. The diaphragm contracts to push the air out.

Insects’ respiratory system is separate from their cardiovascular system. Air enters though small holes called spiracles which open and close and down the trachea to tracheoles. Tracheoles divide until their ends penetrate individual body cells.

Fish obtain oxygen through the water which enters their mouth and passes their gills, filament and lamellae. Lamellae is supplied with capillaries, allowing CO2 and O2 to diffuse in and out.

Question 25

What is the difference between a closed circulatory system and an open circulatory system?

Answer 25

Closed circulatory systems pump blood through enclosed vessels such as arteries, vein and capillaries. This is high pressure and allows efficient delivery of oxygen and waste removal as it is a one way path. Consequently it requires more energy to sustain for vertebrate organisms including amphibians, fish and mammals.

Open circulatory systems pumps haemolymph into haemocoel through open ended vessels. Organs are surrounded by the haemolymph and returned to the heart. This low pressure circulation is less efficient in transporting nutrients and waste but requires less energy. Molluscs and arthropods use this

Question 26

Explain the roles of macroscopic structures in the circulatory system

Answer 26

The heart is a large muscle used to pump blood around the body.
Arteries transport oxygenated blood away from the heart.
Veins transport deoxygenated blood back to the heart.
Capillaries connect arteries and veins and allows gas exchange.

Question 27

Explain the roles of microscopic structures in the circulatory system

Answer 27

Red blood cells carry oxygen in blood
White blood cells fight off infections
Platelets allow clotting to prevent blood loss

Question 28

What is the path of the circulatory system beginning with the left ventricle?

Answer 28

Oxygenated blood from the left ventricles goes up the aorta around the body to exchange oxygen for carbon dioxide. The deoxygenated blood then returns through the superior and inferior vena cava, meeting in the right atrium. The blood goes down the right ventricle and through the pulmonary artery to the right and left lung where oxygen is diffused in and carbon dioxide is diffused out. The oxygenated blood return through pulmonary veins to the left atrium and back to the left ventricle.

Question 29

What is the difference between systemic circulation and pulmonary circulation?

Answer 29

Systemic circulation involves blood travelling to and from the heart to the rest of the body. Pulmonary circulation involves blood travelling to and from the heart to the lungs, connecting with the respiratory system.

Question 30

What are 3 examples of when fluid composition changes?

Answer 30

-Oxygen increase/decrease: passing the lungs for gas exchange and passing tissues and organs
-Nutrient increase/decrease: passing absorbing organ (intestines) and moving through tissues and organs
-urea increase/decrease: Passing the liver and passing the kidney

Question 31

What are 3 examples of when fluid composition changes?