BITSAT Biology Flashcards

24 sample cards from the Biology deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. What is the basic morphology of a typical angiosperm root system vs. shoot system?

   Root system (underground): tap or fibrous roots for anchorage and absorption. Shoot system (aerial): stem with nodes/internodes bearing leaves, buds, flowers, and fruits.

2. What are the three types of aestivation and the parts of a typical flower?

   Aestivation (arrangement of sepals/petals in bud): valvate, twisted, imbricate, vexillary. A typical flower has four whorls: calyx (sepals), corolla (petals), androecium (stamens), and gynoecium (carpels).

3. Differentiate apoplast and symplast pathways of water movement.

   Apoplast: water moves through cell walls and intercellular spaces without crossing membranes (faster). Symplast: water moves through cytoplasm via plasmodesmata, crossing plasma membranes.

4. What is transpiration pull and its role in water ascent?

   The cohesion-tension mechanism: evaporation of water from leaf stomata creates negative pressure (tension) that, via cohesion of water molecules in xylem, pulls a continuous water column upward from roots to leaves.

5. Distinguish macronutrients and micronutrients in plants with examples.

   Macronutrients are needed in large amounts (C, H, O, N, P, K, Ca, Mg, S). Micronutrients are needed in trace amounts (Fe, Mn, Zn, Cu, B, Mo, Cl, Ni).

6. Write the overall balanced equation of photosynthesis.

   6CO2 + 12H2O → (light, chlorophyll) → C6H12O6 + 6O2 + 6H2O. (Simplified: 6CO2 + 6H2O → C6H12O6 + 6O2.)

7. Where do the light reactions and the Calvin cycle of photosynthesis occur?

   Light reactions occur in the thylakoid membranes of chloroplasts (producing ATP, NADPH, O2). The Calvin cycle (dark/light-independent reactions) occurs in the stroma (fixing CO2 into sugar).

8. What is the difference between C3 and C4 plants in CO2 fixation?

   C3 plants fix CO2 directly via RuBisCO into 3-carbon 3-PGA (first product). C4 plants first fix CO2 into 4-carbon oxaloacetate (via PEP carboxylase) in mesophyll, then release CO2 to the Calvin cycle in bundle-sheath cells, minimizing photorespiration.

9. Write the overall equation of aerobic respiration and the net ATP yield per glucose.

   C6H12O6 + 6O2 → 6CO2 + 6H2O + energy. Net yield is about 36–38 ATP per glucose molecule under aerobic conditions.

10. Name the stages of aerobic respiration and where each occurs in a eukaryotic cell.

    Glycolysis (cytoplasm), pyruvate oxidation and Krebs/citric acid cycle (mitochondrial matrix), and oxidative phosphorylation/electron transport chain (inner mitochondrial membrane).

11. Compare aerobic and anaerobic respiration end products.

    Aerobic: CO2 + H2O, ~36–38 ATP. Anaerobic (fermentation): in muscles → lactic acid; in yeast → ethanol + CO2; yields only 2 ATP per glucose.

12. Name the chambers of the human heart and the valves between atria and ventricles.

    Four chambers: right atrium, right ventricle, left atrium, left ventricle. Right AV valve = tricuspid; left AV valve = bicuspid (mitral). Semilunar valves guard the aorta and pulmonary artery.

13. What is the functional unit of the kidney and its primary functions?

    The nephron. It performs filtration (glomerulus/Bowman's capsule), reabsorption, and secretion to form urine, regulating water, ions, and removing nitrogenous wastes (urea).

14. Distinguish asexual from sexual reproduction and give two asexual methods.

    Asexual: single parent, no gametes, offspring genetically identical (clones), fast. Sexual: two parents (usually), gamete fusion, genetic variation. Asexual methods: binary fission, budding, fragmentation, spore formation, vegetative propagation.

15. Name the parts of the human male reproductive system and the main male hormone.

    Testes (sperm + testosterone), epididymis, vas deferens, seminal vesicles, prostate gland, bulbourethral glands, urethra, and penis. Main hormone: testosterone.

16. Name the parts of the human female reproductive system and the site of fertilization.

    Ovaries, fallopian tubes (oviducts), uterus, cervix, and vagina. Fertilization normally occurs in the ampulla of the fallopian tube.

17. Outline the early stages of human embryonic development from zygote to implantation.

    Zygote undergoes cleavage to form a morula, then a blastocyst (with inner cell mass and trophoblast). The blastocyst implants into the uterine endometrium (~day 7); gastrulation then forms the three germ layers.

18. What are the three primary germ layers and one derivative of each?

    Ectoderm (skin epidermis, nervous system), mesoderm (muscles, bones, blood, kidneys), and endoderm (gut lining, liver, lungs).

19. What hormones maintain pregnancy and what triggers parturition?

    Progesterone (with estrogen, hCG, and placental lactogen) maintains pregnancy. Parturition (childbirth) is triggered by the foetal-placental signal leading to oxytocin release, which causes strong uterine contractions (a positive feedback reflex).

20. Classify common contraceptive methods with one example each.

    Barrier (condom, diaphragm), hormonal (oral pills, injections), intrauterine devices (Cu-T, LNG-IUD), natural (rhythm/periodic abstinence), and surgical/sterilization (vasectomy, tubectomy).

21. Define ecology, habitat, and niche.

    Ecology: study of interactions between organisms and their environment. Habitat: the physical place where an organism lives. Niche: the functional role and range of conditions/resources an organism uses (its 'profession').

22. List the ecological levels of organization from simplest to most complex.

    Organism → population → community → ecosystem → biome → biosphere.

23. What are the trophic levels in an ecosystem and the 10% law of energy flow?

    Producers (T1) → primary consumers/herbivores (T2) → secondary consumers (T3) → tertiary consumers (T4) → decomposers. Energy flow is unidirectional; only ~10% of energy is transferred to the next trophic level (Lindeman's 10% law).

24. List the steps of recombinant DNA technology and name two applications in human health.

    Steps: (1) isolation of DNA, (2) cutting with restriction enzymes, (3) inserting into a vector (ligation), (4) transferring into a host (transformation), (5) selection and culturing of transformed cells, (6) extraction of product. Health applications: production of recombinant insulin (Humulin) and gene therapy/vaccines (e.g., recombinant hepatitis B vaccine).

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