Topic 2 - Physiology Flashcards
1
Q
Define and contrast anaerobic and aerobic respiration.
A
- Anaerobic respiration occurs in the absence or reduction of oxygen. Following glycolysis, fermentation occurs to produce and release ATP continuously
- Aerobic respiration occurs with oxygen and releases more ATP
2
Q
Explain why gas exchange is important and what features of gas exchange surfaces increase the rates of diffusion.
A
- Gas exchange involves the replenishment of oxygen and elimination of carbon dioxide
- A large surface area increases diffusion
- A small diffusion distance is preferred
- Fick’s law
3
Q
Describe the main structure used by plants and fungi for gaseous exchange
A
- In plants, exchange occurs through the stomata into the spongy mesophyll layer of leaves where gas diffuses rapidly in air spaces.
- Fungi undergo simple diffusion for gas exchange, and it occurs via mycelium, thin branching roots, and microscopic hyphae that interact with the air pockets in the soil
4
Q
Explain other features of plants and fungi that assist with the process
A
- Aerenchyma, the spaces between cells, in stems relies on pressure for the movement of gases
- Lenticels are pores on woody stems that allow for gases to travel in and out of the plant
5
Q
Describe the main structures of the gas exchange systems of animals
A
- In moist environments, animals with thin tissues rely on gas exchange across their body walls
- In larger species, there are 2 main processes: ventilation and circulation.
- In insects, air enters the body through small openings called spiracles and then travels through a network of tubes called trachea and then even finer tubes called tracheoles, which allows oxygen delivery to tissues and cells.
6
Q
Compare and contrast different gas exchange structures that exist in animals that extract gases from water versus air
A
- Insects can close spiracles to prevent water loss and can also contract their abdomens for ventilation and sucking air inside their bodies
- Lungs have thin walls and are surrounded by many small capillaries to transport oxygen to and carbon dioxide from body tissues. The branching in the lungs provide an increased surface area for diffusion, and is kept moist by surfactants that decrease surface tension to aid in diffusion
- Gills are bunches of filaments covered in lamellae to increase surface area. As water flows over the gills, oxygen diffuses from water into the blood within gill capillaries, and carbon dioxide diffuses from the body into the water to be expelled.
7
Q
Define autotrophs
A
- Organisms capable of producing the majority of the nutrients required for cellular metabolism themselves
8
Q
Define heterotrophs
A
- Organisms that must obtain the majority of their nutrients from other organisms
9
Q
Explain adaptations to nutrient aquation in plants
A
- In autotrophs, chemosynthesis occurs in ecosystems that lack sunlight and have an increased concentration of inorganic compounds. Chemosynthetic organisms live as symbionts in heterotrophic organisms and convert dissolved carbon dioxide into carbs
10
Q
Describe the essential nutrients in animals
A
- Carbohydrate digestion: enzymes break down cards into simple sugars. Glucose can directly enter glycolysis, other simple sugars are converted into sugars that are intermediates of the glycolytic pathway.
- Protein digestion: broken down by enzymes into amino acids, some amino acids enter cellular respiration after losing their amino groups, others are converted into ammonia and are incorporated into waste products.
- Fat digestion: lipids can be produced and broken down into cellular respiration pathways. Phosphorylated glycerol enters glycolysis, and fatty acids enter the citric acid cycle after being converted into acetyl CoA through beta-oxidation.
11
Q
Explain how bacteria and fungi acquire nutrition
A
- Symbiotic relationships with other plants
- Nitrogen fixation: soil-swelling bacteria convert atmospheric nitrogen to ammonia
- Provides plants with forms of nitrogen used to synthesise proteins and nucleic acids
- Ectomycorrhizae covers roots and helps absorb water and minerals
- Arbuscular mycorrhizae are embedded within root tissue which increases contact between plant cells and hyphae
12
Q
Explain how plants excrete waste
A
- Plants can recycle wastes/by-products
- Transpiration controls water homeostasis and facilitates the diffusion of excess oxygen out of plants via the stomata
- Guttation involves the exudation of xylem sap in the form of water droplets through hydathodes found in the margins of leaves
- Mineral compounds can be stored in vacuoles of cells in plant structures like leaves until they shed and die (known as shedding)
13
Q
Explain fungi digestion
A
- Carbon compounds are obtained from non-living organic substrates by absorption of nutrients across their cell wall
- Small molecules accumulate in watery film surrounding hyphae and diffuse through the cell wall
- Macromolecules undergo preliminary digestion before being absorbed by fungal cells
14
Q
Describe the digestive tract in animals
A
- Digestive molecules are moved around the body to where they’re needed via the circulatory system
- In simple guts, water flows from the environment into the body where cells capture food particles from the water
- The foregut intakes and stores food and is where initial stages of chemical and mechanical digestion take place
- In the midgut and hindgut, chemical digestion and absorption of nutrients takes place
15
Q
Describe excretory systems in aquatic environments
A
- Animals excrete nitrogenous waste as ammonia due to high solubility and supply of water
- Echinoderms and Cnidarians rely on passage across the body wall
- In other groups, waste is excreted through tubules leading out their bodies
- In aquatic molluscs, the metanephridia drains nitrogenous waste from the sacs surround the heart, down into the mantle cavity where ammonium rich urine is excreted into surrounding water.
