MODULE 2 Flashcards
What is a unicellular organism?
Single-celled, all life processes occur at the cellular level, can either be prokaryote or eukaryote. (euglena)
What is a colonial organism?
Individual unicellular organisms living in contact with one another, no cell specialisation (volvox)
What is a multi-cellular organism?
Composed of many integrated and independent cells, cell specialisation and division of labour, efficient.
What are the characteristic of unicellular cells?
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
What are the characteristic of colonial cells?
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.
What are the characteristic of multi-cellular cells?
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.
How do unicellular, colonial and multicellular cells obtain nutrients from the environment?
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.
What 5 organelles do all 3 share?
Nucleus, mitochondria, chloroplasts, golgi body and rough endoplasmic reticulum.
What is the evolutionary link between unicellular and multi-cellular organisms?
Colonial
What is cell differentiation?
Cell differentiation occurs in response to specific triggers from the body or from the cell itself.
What is cell specialisation?
Cell specialisation is the process by which cells become specialised in order to perform different functions.
What is the process of cell specialisation?
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.
What are multipotent and pluripotent cells?
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)
What is the relationship between organelles and cell specialisation when referring to multi-cellular organisms?
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.
How does the chloroplast structure within specialised plant cells relate to function?
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.
How does the mitochondria structure within the specialised plant and animal cells relate to function?
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.
What are tissues?
A collection of cells in an organism that have a similar structure and common function (epithelial, nerve, connective, vascular)(dermal, ground, vascular)
What are organs?
A group of tissues that perform a specific function or groups of functions (heart, lungs, kidneys, roots, stems, leaves, flowers)
What are organ systems?
A group of organs that work together to carry out a particular task (respiratory system, shoot and root system)
How does cell shape relate to its function?
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
How does the structure of red blood cells relate to differentiation and specialisation?
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
How does the structure of white blood cells relate to differentiation and specialisation and the cell’s function?
They are globular in shape with structures that help attach and engulf pathogens and prevent disease.
How does the structure of neurons relate to differentiation, specialisation and function?
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.
How does the structure of sperm relate to differentiation, specialisation and function?
They consist of 3 parts, the head the midpiece and the tail. The tail allows for fast moving into the female egg, fertilising it.
How does the structure of epithelial cells relate to differentiation, specialisation and function?
Hair-like cilia capture and help move particles out of the body
How does the digestive tract as an organ relate to differentiation, specialisation and function?
THe highly folded digestive tract and intestines increase the surface area over which physical and chemical digestion can occur.
How does the structure of palisade cells relate to differentiation, specialisation and function?
They are vertically elongated with a high number of chloroplasts- primary site of photosynthesis, increasing surface area due to thylakoids and elongated shape
How does the structure of root hair cells relate to differentiation, specialisation and function?
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
How does the structure of guard cells cells relate to differentiation, specialisation and function?
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
How does the structure of companion cells relate to differentiation, specialisation and function?
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.
How does the organ of the leaf relate to differentiation, specialisation and function?
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.
What is the hierarchy of multicellular organisms?
cells-tissues-organ-organ system-organism
Why do multicellular organisms require cell specialisation?
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.
What happens when large cells have a low SA:Volume ratio?
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.
Justify the hierarchical structure of MC organisms
- 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.
What is MRS GREN?
The features of all living organisms
Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition
What are autotrophs?
An organism that is capable of synthesizing its own food (organic) from inorganic substances. They are the producer.
What are heterotrophs?
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
What are photoautotrophs and chemoautotrophs?
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.
What are microscopic and macroscopic structures?
Macroscopic- Can be seen with the naked eye
Microscopic- Can only be seen through microscope
Name the macroscopic and microscopic structures in a plant.
Macroscopic- vein, lamina, tip, flower, roots, tip
Microscopic- cell wall, nucleus, chloroplasts, pollen grain, root hair, mesophyll, vascular bundle, guard cells etc
Explain the function of macroscopic structures in a leaf.
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.
Explain the function of microscopic structures in a leaf.
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.
Explain the function of macroscopic structures in a stem
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.
Explain the function of microscopic structures in a stem
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.
Explain the function of macroscopic structures in a flower
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.
Explain the function of microscopic structures in a flower
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.
Explain the function of microscopic and macroscopic structures in roots
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.
What are radioisotopes? How do they help trace the products of photosynthesis?
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.
Where does gas exchange occur in plants?
Stomata (leaves) and lenticels (trunks and branches)
What is digestion?
The process by which food is broken down into smaller pieces and then into simple compounds that can be absorbed by the body.
What is the difference between chemical and physical digestion?
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)
What is a herbivore?
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
What is a carnivore?
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.
What is an omnivore?
An animal whose primary food source consists of plants and animals
Teeth are a combination of both
What characterises a herbivore digestive system?
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
What characterises a carnivore’s digestive system?
Their digestive system is simple as meat is easily digested, it is short and doesn’t have a caecum
What characterises an omnivores digestive system?
Due to mixed diet, their digestive tract is somewhere between the herbivore and carnivore.
What is a nutrient?
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.
What is a mineral?
Minerals are naturally occurring inorganic nutrients that have a biochemical function. For
example, water, iron, sodium, and calcium.
What is a vitamin?
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).
Where is the majority of nutrients from digested food absorbed?
The small intestine
How are nutrients absorbed from food in the small intestine?
Nutrients pass through the wall of the small intestine (villi) into blood vessels which then
distribute the nutrients to the rest of the body.
What are the parts of the small intestine?
The parts of the small intestine include the duodenum, jejunum and the ileum.
What occurs in the duodenum?
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.
What does the jejunum do?
-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.
What does the illeum do?
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.
What does the colon do?
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.
What are the similarities in the nutrient requirements for hetero and autotrophs?
Need carbs, proteins, lipids and nucelic acids
CHONPS-carbon, hydrogen, oxygen, nitrogen, phosphorous, sulfur
-liquid water
What are the differences in the nutrient requirements for hetero and autotrophs?
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
What are the differences between heterotrophs and autotrophs in terms of photosynthesis and cellular respiration?
Autotrophs require carbon dioxide for photosynthesis AND oxygen for cellular respiration.
Heterotrophs require ONLY oxygen for cellular respiration.
Where are the xylem and phloem located?
Phloem- Outer side of vascular bundle
Xylem- Centre of vascular bundle
What is cohesion? What is adhesion?
Cohesion- The bonding between substances
Adhesion- the bonding between different substances
What occurs in the transpiration-cohesion-tension theory?
- Water moves into the roots through osmosis
- Water evaporates from the plant via transpiration
- As a result of cohesive and adhesive forces, water molecules are drawn up the xylem.
What is the transpiration stream?
The movement of the column of water up the stem due to the evaporative pull of transpiration.
What is translocation?
Translocation is the movement of sugars (produced during photosynthesis) from leaves to other tissues
throughout the plant.
Source (leaves) to sink (roots)
What occurs in this process?
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
What was Joseph Priestly’s hypothesis? What was his conclusion?
‘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.
What was Nicolas de Sassure’s hypothesis? What was his conclusion?
‘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.
What was Melvin Calvin’s hypothesis? What was his conclusion?
‘Photosynthesiss consists of a series of reactions’
He used a lollipop apparatus and radioactive c14 to propose the Calcin Cycle or light independent reactions
What are the features of gas exchange surfaces?
→ 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
Structure/function alveoli gas exchange
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.
Insects- gas exchange
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.
