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Flashcards by milicevic.marija, updated more than 1 year ago
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Created by milicevic.marija
over 9 years ago
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| Question | Answer |
| What is the structure of a leaf? | Palisade mesophyll Upper epidermis Xylem Phloem Stoma Guard Cells Spongy Mesophyll |
| Define transpiration | Loss of water vapour from the leave and stem of plants |
| Name of plants adapted to grow in dry habitats | Xerophytes |
| How do plants increase absorption area? | By branching of roots and growth of root hairs |
| Name the three ways ions move | diffusion of mineral ions mass flow of water carrying ions Fungal hyphae and then into roots |
| Name mineral ions that plants absorb | Potassium Phosphate Nitrate |
| What do root hair cells contain in their plasma membrane? | Mitochondria and protein pumps |
| What can sometimes limit rate of absorption of mineral ions? | Rate at which ions move through soil to root |
| How do ions enter roots? | Concentration in soil is much lower than inside root cells, so absorbed through active transport |
| Outline the differences between dicotyledons and monocotyledons | |
| Function and distribution of upper epidermis | Main function is water conservation Distributed on top of leaves where light intensity and heat are greatest |
| Function and distribution of palisade mesophyll | It is main photosynthetic tissue Distributed on upper half of leaf where light is greatest |
| Function and distribution of spongy mesophyll | Main site of gas exchange Lower half of leaf near stomatal pores |
| Function and distribution of vascular tissue | Transport of water and products Found in middle of leaf |
| What are stem organs? | Plant specifically modified roots that store food or water carrot |
| What are stem tubers? | Horizontal underground stems that store carbohydrates potato |
| What are bulbs? | Modified leaf bases that contain layers called scales onions |
| What are succulents | Plants with modified leaves or stems to enable water storage |
| What are tendrils? | Plants with modifications to their leaf or stems for climbing support vines |
| What is a meristem? | Tissue in plants consistently of undifferentiated cells found in growth zones |
| What are meristematic cells? | Analogous stem cells in animals |
| What type of meristem do dicotelydons have? | Apical and lateral meristems |
| What is phototropism? | Organism growing or turning towards light |
| What are auxins? | Hormones produced by tip of plant to mediate phototropism |
| Explain role of auxins | Auxin makes cells enlarge or grow and, in the shoot, are eradicated by light The accumulation of auxin on the shaded side of a plant causes this side only to lengthen, resulting in the shoot bending towards the light Auxin causes cell elongation by activating proton pumps that expel H+ ions from the cytoplasm to the cell wall The resultant decrease in pH within the cell wall causes cellulose fibres to loosen (by breaking the bonds that hold them together) This makes the cell wall flexible and capable of stretching when water influx promotes cell turgor Auxin can also alter gene expression to promote cell growth (via the upregulation of expansins) |
| What is pollination? | Transfer of protein grains from anther to stigma, often facilitated by animals, wind or water movement |
| What is fertilisation? | Fusion of male gamete nuclei with female gamete to form a zygote |
| What is seed dispersal? | Fertilised ovules form seeds which move away from parental plant before germination, reducing competition for resources Mechanisms: fruit, wind, water and animals |
| Draw and label diagram of dicotyledonous seed | |
| What are conditions needed for germination of a typical seed? | Oxygen: aerobic respiration Water: metabolically activate cells Temp: optimal function of enzymes |
| 3 ways of which terrestrial plants support themselves | Thickened cellulose: provides extra structural support Cell turgor: increased hydrostatic pressure, makes cell turgid lignified xylem: extra support |
| What do guard cells regulate? | Opening and closing of stomata |
| Which plant hormone causes closing of stomata? | Abscisic acid |
| What are the abiotic factors? | Light, temp, wind and humidity |
| How does light/temp affect rate of transpiration? | Light: increased light intensity increases rate of transpiration. Light stimulates opening of stomata. Some light energy is absorbed and converted into heat. Temp: increased heat, increases rate of transpiration. Higher temp causes increase in water vapour and evaporation from surface of leaf. Increase in diffusion of water temp. out of leaf |
| How does wind/humidity affect rate of transpiration? | Wind: greater wind, greater rate of transpiration. Wind removes water vapour, increasing rate of diffusion. Humidity: higher humidity, decreases rate of transpiration. Reduces rate of diffusion of water vapour form inside the leaf. |
| Outline 4 adaptions of xerophytes | Reduced leaves Rolled leaves Thick waxy cuticle low growth |
| Outline the role of phloem | Sugars and amino acids move from source into phloem. Actively loaded into phloem by companion cells, creating high conc which draws water from xylem via osmosis. Sap volume and pressure increase to create mass flow which drives the sap along the phloem. Molecules unloaded and stored in sink. Sucrose loaded as starch, water back to xylem. |
| Describe the metabolic process during germination of starchy seed | absorption of water, causes gibberlin to be produced. (gibberlin causes synthesis of amylase (breaks starch down into maltose)) Maltose is transported to embryo where either hydrolysed to glucose or polymerised to cellulose. Stored proteins and lipids will also be hydrolysed by addition of water to form enzymes, triglycerides and phospholipids. Germination uses food stored in cotyledons as energy source until developing shoot reaches light and can begin to photosynthesise. |
| What are two forms of phytochrome? | Red (Pr) absorbs red light and is converted to far red (Pfr) Far red (Pfr) absorbs far red light and is converted to red (Pr) Pfr is active form of phytochrome Pr is inactive form |
| How is flowering controlled in long-day and short-day plants? including phytochrome | Flowering is controlled by phytochrome which is affected by light. Sunlight contains more red light so the Pfr form is predominant during the say with gradual reversion to Pr form occurring at night. Long-day plants - active Pfr is a promoter of flowering so flowering is induced when night is less critical length Short-day plants - active Pfr is inhibitor of flowering, so is induced when night is greater than critical length |
| How does water uptake occur through root system? | Plants take up water and essential minerals via roots, need maximum surface area in order to optimise this uptake. Monocotyledon has a fibrous, highly branching structure which increases surface area. Dicotyledon root has main tap root which can penetrate deeply into soil to access deeper reservoirs of water and mineral as well as lateral branches. Root hairs: carrier proteins and ion pumps in plasma membrane and many mitochondria within cytoplasm (aid active transport) |
| Explain process of mineral ion absorption from the soil into roots by active transport | Fertile soil contains negatively charged particles which positively charged minerals attach to. Root cells contain proton pump that actively pulp H+ ions into surrounding soil, which displaces positively charged minerals allowing absorptions. Mode of absorption is indirect AT. OR via direct AT using protein pumps to actively translocate ions against conc gradient |
| What is cohesion? | Water molecules are weakly attracted to each other via hydrogen bonds |
| What is adhesion? | Water molecules form hydrogen bonds with the xylem cell wall |
| How is water carried by transpiration stream? Part 1 | Some light energy absorbed by leaves changes into heat converting water in spongy mesophyll to water. Vapour diffuses out of stomata and evaporates creating a negative pressure gradient in leaf. New water is drawn from xylem, which is replaces by water from the roots. Flow of water through xylem from roots to leaf is called transpiration stream. Water rises through xylem vessels because of cohesion and adhesion. These properties create suction effect of xylem |
| Part 2 | Xylem has a specialised structure to facilitate transpiration: inner lining is composed of dead cells that have fused to create a continuous tube. These cells lack cell membrane allowing water to enter xylem freely. Outer layer is perforated allowing water to move out of xylem into leaves. Outer cell wall: annular lignin rings which strengthen xylem against tension created by transpiration stream |
| Draw a diagram of stem and leaf tissue |
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