FINAL - Plants / Nutrition Flashcards
Explain the process of phototropism in plants, including the role of auxin.
- Auxin is a plant hormone produced by the shoot tip
- Auxin efflux pumps set up concentration gradient
- Transport of hydrogen ions from cytoplasm to cell wall - Decrease in pH breaks bonds in cell wall fibers
- Makes wall fibers flexible
- Auxin makes cells grow
- Gene expression is altered by auxin to promote cell growth
- Shoot tip senses direction of light and grows towards it
What is the relationship between flowers and pollinators.
- Mutualistic
- Both species benefit from each other
- animal gets nectar/ pollen and flower is pollinated/ fertilized
Describe the conditions needed for seed germination.
- Water to rehydrate seed
- gibberellin released after water absorbed
- Oxygen for aerobic respiration
- Warmth needed to speed up enzyme activity
- Warmth indicates that its spring - SOME: fire, pass through digestion
Explain the process of photoperiodism in long-day and short-day flowering plants (including the role of phytochrome).
- Flowering is affected by absence of light
- Phytochrome exists in two forms
- Pr = inactive and Pfr = active - Pr converted to Pfr in day light
- Sunlight has more red light so Pfr dominates during the day
- Pfr reverts to Pr in the darkness
- Long-Day = flowering induced by dark periods shorter than critical length (day is long)
- Short-day = flowering induced by dark periods longer than critical length
Explain apical growth in plant shoots, including the role of auxin.
- Apical growth occurs in apical meristems (at tips of the roots and shoots)
- due to cell elongation and repeated cell division (mitosis and cytokinesis) bc auxin - Differentiation of meristem makes stem tissues and structures (leaves and flowers)
- growth occurs in nodes with remaining tissue forming an inactive axillary bud
- buds have the potential to form new shoots, with leaves and flowers
Discuss the use of micropropagation to reproduce plants.
Pros
- More reliable than selective breeding
- Production of virus-free strains
- propagation of rare/endangered species
Cons
- Expensive
- No genetic variation
Draw a labelled diagram with the functions of the parts of an animal pollinated flower.
Stigma: Pollen “landing pad” (sticky)
Style: Supports the stigma
Ovary: Produces female sex cells (ovules) by meiosis
Anther: Produces male sex cells (pollen) by meiosis
Filament: Supports the anther
Petals: Attracts pollinators
Sepals: Protect developing flower (while in the bud)
Distinguish between pollination and fertilization in flowering plants.
Pollination: Transfer of pollen from the anther to the stigma
Fertilization: When two haploid nuclei fuse, male pollen grain fuses with the female ovule to produce a diploid zygote
Outline how knowledge of photoperiodism can be used to induce short-day plants to flower out of season.
- Plants are purposefully covered with a black cloth for 12-15 hours a day until flower buds begin to grow
- Pfr inhibits flowering in short day plants
- Pfr reverts to Pr in the darkness
- Less Pfr in short-day = flowering (means long night and less red/sun light)
Distinguish essential and non-essential nutrients.
Essential: CANNOT be synthesized by the human body
Non-Essential: CAN be synthesized by the human body
Discuss the causes and consequences of malnutrition, including protein deficiency malnutrition.
Cause: A deficiency, imbalance, or excess nutrients in the diet
Consequence: Obesity (leads to CHD), Starvation (leads to break down of body tissues)
Protein Deficiency: muscle loss, stunted growth
Outline how leptin controls appetite and the consequences of leptin desensitization.
- Leptin secreted by adipose tissue
- Leptin targets cells in hypothalamus to inhibit appetite
- Level is controlled by amt of adipose tissue
- More adipose tissue = higher blood leptin concentration
- Desensitized: less likely to recognize when full, more likely to overeat (obesity)
Compare and contrast vitamins and dietary minerals.
- BOTH are obtained through the diet
- Vitamins are organic compounds
- Minerals are Inorganic compounds
Explain how to determine the energy content of food.
- Calorimetry - burning a food sample // measuring the heat energy released from the burning food using a calorimeter
- Heat from the burning food is transferred to the water
- Temperature increase of the water is used to calculate the energy content of the food:
Mass of water (g) x 4.2 (J/g℃) x Temp increase (℃)
Discuss the causes and treatment of PKU.
Causes: inherited genetically, deficient in phenylalanine hydroxylase (cannot convert into tyrosine)
Treatments: diet rich in tyrosine / low in phenylalanine
