MODULE 2

Question 1

What is a unicellular organism?

Answer 1

Single-celled, all life processes occur at the cellular level, can either be prokaryote or eukaryote. (euglena)

Question 2

What is a colonial organism?

Answer 2

Individual unicellular organisms living in contact with one another, no cell specialisation (volvox)

Question 3

What is a multi-cellular organism?

Answer 3

Composed of many integrated and independent cells, cell specialisation and division of labour, efficient.

Question 4

What are the characteristic of unicellular cells?

Answer 4

Single celled, consistient number and type of organelles within the cells, division of labour occurs at the organelle level, the cell body is exposed to the environment on all sides, restricted in size due to SA Vol, can regenerate well, and the cell role is the same as the organism

Question 5

What are the characteristic of colonial cells?

Answer 5

Numerous single cells, consistent number and type of organelles within the cells of the colony, division occurs at the organelle level, intermediate exposure to the environment depending on location within colony, cells are restricted in size due to SA vol, but colony can be large, can regenerate well, short life span and same role for itself and organism.

Question 6

What are the characteristic of multi-cellular cells?

Answer 6

Numerous cells, variation in number and type of organelles dependent on cell specialisation, division of labour occurs at the cellular, tissue, organ or system level, only outer cell are specialised to face the environment, can be large in size (specialised roles), capacity to regenerate is lost with increasing specialisation. They have a double role for themselves and the organism.

Question 7

How do unicellular, colonial and multicellular cells obtain nutrients from the environment?

Answer 7

Unicellular- direct diffusion, endocytosis, active transport
Colonial-direct diffusion, endoyctosis, active transport
Multicellular- organ systems work together to take in nutrients and to distribute the products throughout the organism.

Question 8

What 5 organelles do all 3 share?

Answer 8

Nucleus, mitochondria, chloroplasts, golgi body and rough endoplasmic reticulum.

Question 9

What is the evolutionary link between unicellular and multi-cellular organisms?

Answer 9

Colonial

Question 10

What is cell differentiation?

Answer 10

Cell differentiation occurs in response to specific triggers from the body or from the cell itself.

Question 11

What is cell specialisation?

Answer 11

Cell specialisation is the process by which cells become specialised in order to perform different functions.

Question 12

What is the process of cell specialisation?

Answer 12

Differentiation of the stem cells occurs and they develop suitable structural features that allow them to carry out their specific functions.
The genetic information that is activated depends on the location of the undifferentiated cells in the body of the organism-cells in the outer layers become skin cells, cells beneath that become muscle cells.

Question 13

What are multipotent and pluripotent cells?

Answer 13

Pluripotent- cells that give rise to all of the cell types that make up the body (embryonic)

Multipotent-Cells that can develop into more than one cell type, but are more limited than pluripotent cells (adult stem cells found in bone marrow)

Question 14

What is the relationship between organelles and cell specialisation when referring to multi-cellular organisms?

Answer 14

Variation in number and type of organelles is dependent on cell specialisation. It also varies depending on whether it is a plant or an animal cell.

Question 15

How does the chloroplast structure within specialised plant cells relate to function?

Answer 15

The highly folded inner membranes of the chloroplasts named the thylakoids increase the surface area. More surface area, means more space for these reactions to take place, there fore more glucose is produced, and the function of the organism is optimised.

Question 16

How does the mitochondria structure within the specialised plant and animal cells relate to function?

Answer 16

The highly folded inner membranes of the mitochondria are named the cristae to increase the surface area. More surface area, means more space for these reactions to take place, there fore more ATP is produced, more cellular respiration, and the function of the organism is optimised.

Question 17

What are tissues?

Answer 17

A collection of cells in an organism that have a similar structure and common function (epithelial, nerve, connective, vascular)(dermal, ground, vascular)

Question 18

What are organs?

Answer 18

A group of tissues that perform a specific function or groups of functions (heart, lungs, kidneys, roots, stems, leaves, flowers)

Question 19

What are organ systems?

Answer 19

A group of organs that work together to carry out a particular task (respiratory system, shoot and root system)

Question 20

How does cell shape relate to its function?

Answer 20

Cells may be flattened (tissues lining our air sacs) or elongated (photosynthesis cells in leaves_ giving the cell a greater SA V than cube shaped cells, causing an efficient exchange of substances

Question 21

How does the structure of red blood cells relate to differentiation and specialisation?

Answer 21

Their size and round shape makes them easily transportable through the capillary bed of our circulatory system efficiently meaning oxygen is carried around the body

Question 22

How does the structure of white blood cells relate to differentiation and specialisation and the cell’s function?

Answer 22

They are globular in shape with structures that help attach and engulf pathogens and prevent disease.

Question 23

How does the structure of neurons relate to differentiation, specialisation and function?

Answer 23

They have long extensions that extend out from the cell body (dendrites) that receive signals and conduct them towards the body. This structure allows signals to be transmitted throughout the body.

Question 24

How does the structure of sperm relate to differentiation, specialisation and function?

Answer 24

They consist of 3 parts, the head the midpiece and the tail. The tail allows for fast moving into the female egg, fertilising it.

Question 25

How does the structure of epithelial cells relate to differentiation, specialisation and function?

Answer 25

Hair-like cilia capture and help move particles out of the body

Question 26

How does the digestive tract as an organ relate to differentiation, specialisation and function?

Answer 26

THe highly folded digestive tract and intestines increase the surface area over which physical and chemical digestion can occur.

Question 27

How does the structure of palisade cells relate to differentiation, specialisation and function?

Answer 27

They are vertically elongated with a high number of chloroplasts- primary site of photosynthesis, increasing surface area due to thylakoids and elongated shape

Question 28

How does the structure of root hair cells relate to differentiation, specialisation and function?

Answer 28

They have no chloroplasts and have a large surface area to speed up osmosis- more area equals more absorption of water and minerals into the soil

Question 29

How does the structure of guard cells cells relate to differentiation, specialisation and function?

Answer 29

They are dispersed through the epidermis in pairs and in between each pair is a small opening called the stoma that contains chloroplasts. The guard cells regulate the opening and closing of the stoma, also regulating the rate of transpiration

Question 30

How does the structure of companion cells relate to differentiation, specialisation and function?

Answer 30

Found between sieve tubes with a large nucleus and high numbers of mitochondria and gaps in the cell wall. The lots of mitochondria mean more energy is created and they can continually control the movement of sugars within the phloem.

Question 31

How does the organ of the leaf relate to differentiation, specialisation and function?

Answer 31

Various specialised tissues- specialised cells carrying our specific functions. -underneath the upper epidermis containing lots of chloroplasts for photosynthesis-lower epidermis with the stoma and the guard cells expand and contract to prevent water loss -tissues of xylem and phloem aid in transporting the energy obtained from photosynthesis in the palisade cells throughout the plant. They all work together.

Question 32

What is the hierarchy of multicellular organisms?

Answer 32

cells-tissues-organ-organ system-organism

Question 33

Why do multicellular organisms require cell specialisation?

Answer 33

Passive transport is unable to address the life requirements of the organism due to the low SA volume ratio. Different cells need to carry out different functions to that the organism can function effectively and efficiently. Therefore, cells need to be specialised for these functions.

Question 34

What happens when large cells have a low SA:Volume ratio?

Answer 34

Relying upon simple diffusion and osmosis are unable to meet the needs of the cell. This causes the cell to die, or it develops specialised systems in order to meet the needs of the organism as a whole.

Question 35

Justify the hierarchical structure of MC organisms

Answer 35

- There is a lot of diversity in the size of multi-cellular organisms - Some insects are millimetres in length, whilst blue whales can reach over 25 metres and weight 150 tonnes. - As size increases, the passive processes of diffusion and osmosis are insufficient in meeting the needs of the organism such as MRS GREN. - As a consequence in order to increase in size, tissues, organs and organ systems have evolved to take on roles that meet the needs of the organism. Without hierarchical organisation, organisms would be limited in size.

Question 36

What is MRS GREN?

Answer 36

The features of all living organisms | Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition

Question 37

What are autotrophs?

Answer 37

An organism that is capable of synthesizing its own food (organic) from inorganic substances. They are the producer.

Question 38

What are heterotrophs?

Answer 38

An organism that can't produce its own food (organic) through photosynthesis and instead obtains its nutrition through consuming other living or dead organisms. There are various groups including herbivores, carnivores, omnivores and decomposers etc

Question 39

What are photoautotrophs and chemoautotrophs?

Answer 39

PA obtain the energy required for carbon fixation from sunlight. (General plant) CA obtain energy required for carbon fixation from inorganic chemical reactions. For example, methanogens generate ATP by synthesizing methane in anoxic conditions by reducing carbon dioxide with oxygen.

Question 40

What are microscopic and macroscopic structures?

Answer 40

Macroscopic- Can be seen with the naked eye | Microscopic- Can only be seen through microscope

Question 41

Name the macroscopic and microscopic structures in a plant.

Answer 41

Macroscopic- vein, lamina, tip, flower, roots, tip | Microscopic- cell wall, nucleus, chloroplasts, pollen grain, root hair, mesophyll, vascular bundle, guard cells etc

Question 42

Explain the function of macroscopic structures in a leaf.

Answer 42

Each leaf has multiple layers including the mesophyll which contains cells with high numbers of chloroplasts. As a result of this high chloroplast concentration, the leaf is the primary plant organ involved in photosynthesis.

Question 43

Explain the function of microscopic structures in a leaf.

Answer 43

A stomate is an opening on the leaf's surface. Each stomate is surrounded by 2 guard cells that can expand and contract, changing the size of the opening. As a result, the plant can control the loss of water through transpiration.

Question 44

Explain the function of macroscopic structures in a stem

Answer 44

The stem contains vascular tissue for example the xylem and the phloem. As a result, the plant is able to move water and dissolved substances from the roots upwards in the xylem such as products of photosynthesis around the plant where they're required through the phloem.

Question 45

Explain the function of microscopic structures in a stem

Answer 45

The xylem are dead and hollow and the phloem is living containing sieve plates and companion cells. As a result, the xylem are able to transport water and dissolved substances up through the transpiration stream and cohesive and adhesive forces.

Question 46

Explain the function of macroscopic structures in a flower

Answer 46

The flower is the reproductive organ of the plant. Each flower has female and male components. As a result, pollination occurs when pollen from the male anthe is transferred to the female stigma.

Question 47

Explain the function of microscopic structures in a flower

Answer 47

The filament and anthe are the male reproductive structures of a flower called the stamen. The filament is a long slender structure that supports the anthe, an oval shaped structure where the pollen develops. As a result, pollen is exposed to pollinators such as insects, birds or wind.

Question 48

Explain the function of microscopic and macroscopic structures in roots

Answer 48

The roots are an organ system. the main root of a plant is called the primary root and the others are called secondary roots. In each root there is vascular tissue connecting the roots with the rest of the plant. Root hairs are elongated microscopic outgrowths from the outer layer of cells in a root. As a result, the root hairs increase the surface area over which water and dissolved nutrients enter the plant.

Question 49

What are radioisotopes? How do they help trace the products of photosynthesis?

Answer 49

Forms of an element that emit radiation which can be detected by a number of means. They act as tracers and are used to follow the pathways of molecules involved in photosynthesis.

Question 50

Where does gas exchange occur in plants?

Answer 50

Stomata (leaves) and lenticels (trunks and branches)

Question 51

What is digestion?

Answer 51

The process by which food is broken down into smaller pieces and then into simple compounds that can be absorbed by the body.

Question 52

What is the difference between chemical and physical digestion?

Answer 52

Physical digestion: The breakdown of food into smaller pieces without any change to the molecular structure of the food (chewing, peristalis, churning etc) Chemical digestion:Breakdown of food by stomach)

Question 53

What is a herbivore?

Answer 53

An animal whose primary food source is plant based The molars are wider and flatter, designed to grind plant material, sharp incisors for tearing plants

Question 54

What is a carnivore?

Answer 54

An animal whose primary food source is from the killing and eating of other animals Canine teeth are long and sharp, making it easy to rip and tear meat from the bones of their prey.

Question 55

What is an omnivore?

Answer 55

An animal whose primary food source consists of plants and animals Teeth are a combination of both

Question 56

What characterises a herbivore digestive system?

Answer 56

Their consumption of plant material is difficult to digest due to cellulose content. It is a long tract with an oversized caecum, containing microflora breaking down the cellulose by fermentation

Question 57

What characterises a carnivore's digestive system?

Answer 57

Their digestive system is simple as meat is easily digested, it is short and doesn't have a caecum

Question 58

What characterises an omnivores digestive system?

Answer 58

Due to mixed diet, their digestive tract is somewhere between the herbivore and carnivore.

Question 59

What is a nutrient?

Answer 59

A substance an organism must obtain from the environment, or from a dietary source, since as it is unable to synthesize it. For example, minerals, vitamins, and essential amino acids.

Question 60

What is a mineral?

Answer 60

Minerals are naturally occurring inorganic nutrients that have a biochemical function. For example, water, iron, sodium, and calcium.

Question 61

What is a vitamin?

Answer 61

A low molecular weight organic compound, required in trace amounts, that is essential for normal growth and metabolic processes. For example, vitamin C (water soluble), and vitamin D (fat soluble).

Question 62

Where is the majority of nutrients from digested food absorbed?

Answer 62

The small intestine

Question 63

How are nutrients absorbed from food in the small intestine?

Answer 63

Nutrients pass through the wall of the small intestine (villi) into blood vessels which then distribute the nutrients to the rest of the body.

Question 64

What are the parts of the small intestine?

Answer 64

The parts of the small intestine include the duodenum, jejunum and the ileum.

Question 65

What occurs in the duodenum?

Answer 65

The duodenum is the first and shortest segment of the small intestine. It receives chyme from the stomach. It is very active in chemical digestion due to the mix of enzymes from the stomach, liver, gall bladder and pancreas.

Question 66

What does the jejunum do?

Answer 66

-absorption of nutrients such as proteins, carbohydrates, amino acid, sugar, fatty acid particles, vitamins and minerals. The villi of the jejunum are longer than those in the duodenum and ileum = increased surface area. The surface are of the jejunum is also increased due to large circular folds called plicae circulares.

Question 67

What does the illeum do?

Answer 67

``` Absorbs mainly vitamin B12 and other water soluble vitamins, bile salts, and nutrients that were not absorbed in the jejunum. Secretes enzymes, which are responsible for the final breakdown of carbohydrates and proteins. Muscular contractions (peristalsis) prevent the back flow ofundigested food and propel undigested food forward into the large intestine. ```

Question 68

What does the colon do?

Answer 68

Large amounts of water and electrolytes are absorbed in the ascending colon transforming it into a mush-like consistency. It continues to solidify further as it passes through the transverse and descending colon.

Question 69

What are the similarities in the nutrient requirements for hetero and autotrophs?

Answer 69

Need carbs, proteins, lipids and nucelic acids CHONPS-carbon, hydrogen, oxygen, nitrogen, phosphorous, sulfur -liquid water

Question 70

What are the differences in the nutrient requirements for hetero and autotrophs?

Answer 70

The difference is in the means of accessing nutrients - Autotroph- comes through the leaves, plants, o2 in the air, splitting of water etc - Heterotroph-digestion of food

Question 71

What are the differences between heterotrophs and autotrophs in terms of photosynthesis and cellular respiration?

Answer 71

Autotrophs require carbon dioxide for photosynthesis AND oxygen for cellular respiration. Heterotrophs require ONLY oxygen for cellular respiration.

Question 72

Where are the xylem and phloem located?

Answer 72

Phloem- Outer side of vascular bundle | Xylem- Centre of vascular bundle

Question 73

What is cohesion? What is adhesion?

Answer 73

Cohesion- The bonding between substances | Adhesion- the bonding between different substances

Question 74

What occurs in the transpiration-cohesion-tension theory?

Answer 74

1. Water moves into the roots through osmosis 2. Water evaporates from the plant via transpiration 3. As a result of cohesive and adhesive forces, water molecules are drawn up the xylem.

Question 75

What is the transpiration stream?

Answer 75

The movement of the column of water up the stem due to the evaporative pull of transpiration.

Question 76

What is translocation?

Answer 76

Translocation is the movement of sugars (produced during photosynthesis) from leaves to other tissues throughout the plant. Source (leaves) to sink (roots)

Question 77

What occurs in this process?

Answer 77

Step 1. Active transport of sugars from photosynthetic cells into phloem Step 2. Osmosis of water from xylem into phloem Step 3. Flow of sugar in all directions around plant Step 4. Active transport of sugars into non-photosynthetic cells -moving from high to low pressure

Question 78

What was Joseph Priestly's hypothesis? What was his conclusion?

Answer 78

'A plant restores the air for breathing animals' He observed that without a plant in the bell jar, both a candle and the mouse would die. He concluded that the plant restpres the air that breathing animals and candles remove.

Question 79

What was Nicolas de Sassure's hypothesis? What was his conclusion?

Answer 79

'A plants growth requires both h2o and co2.' He observed that a plant in a closed container for a fixed period of time would have lower levels of co2 but plant has more mass. He concluded that h2o and co2 create glucose.

Question 80

What was Melvin Calvin's hypothesis? What was his conclusion?

Answer 80

'Photosynthesiss consists of a series of reactions' He used a lollipop apparatus and radioactive c14 to propose the Calcin Cycle or light independent reactions

Question 81

What are the features of gas exchange surfaces?

Answer 81

→ Large surface area relative to the volume of the organism → Thin to minimise diffusion pathway → Moist as gases can only cross cell membranes when they are dissolved → Close contact with blood supply

Question 82

Structure/function alveoli gas exchange

Answer 82

Tiny air sacs, the point at which oxygen/carbon dioxide gas exchange occurs. Blood with high CO2 concentration diffuses as it travels past the alveoli to then be exhaled. Oxygen then diffuses into the blood which has a low O2 concentration.

Question 83

Insects- gas exchange

Answer 83

Breathe through spiracles (small holes). Spiracles can be opened and closed to prevent water loss and opened when greater respiration is needed, waste CO2 also exits the spiracles. The tracheoles divide until their microscopic ends penetrate into individual body cells.