Biology

• combine with the eyepiece lens to increase magnification levels


  objective
• What is Mitosis?

  Is a cell division which occurs during development and growth.It produces two daughter cells which are genetically identitical to the parent cell.
• Endocytosis

  The process where vesicle transports molecule into the membrane.
• Diffusion

  The process by which substances move from a region of high concentration to a region of low concentration.
• Active transport- is a movement of molecules across a membrane from a region of their lower concentration to a region of their higher concentration, i.e., against the concentration gradient.
• a normal sperm cell contains


  either one x or one y chromosome
• egg cells will always have

  x chromosome
• Variation


  differences that exist between members of the same species.
• contininuous variation


  For any species a characteristic that changes gradually over a range of values shows continuous variation, for example, height, weight, heart rate, finger length and leaf length.
• Discontinuous variation-


  A characteristic of any species with only a limited number of possible values, for example, tongue rolling, finger prints, eye colour and blood groups.
• two structures are found only in plant cells


  Chloroplast and cell wall
• feature of monocotyledons?

  One cotyledon, Fibrous roots, scattered vascular, parallel veins and flower arranges in multiples of 3.
• products of the photosynthesis reaction is used to drive

  the respiration reactions in the mitochondria?

  Carbon dioxide and glucose
• plant shoot growing towards sunlight?

  Phototropism
• Phototropism


  Phototropism is the growth response of a plant in response to light direction.Stems show positive phototropism while most roots show negative phototropism.
• Hydrotropism


  s the growth response of a plant to water. Roots exhibit positive hydrotropism
• Chemotropism


  is the growth response of a plant to a particular chemical. Roots grow toward useful minerals in the soil
• Thigmotropism


  growth movements made by plants in response to contact/ touch with a solid object.
• Red blood cells are different from white blood cells in that they

  do not have nucleus.
• formed during the fertilisation of two gametes?

  A zygote
• The family planning method that also gives protection from sexually transmitted infections is the use of

  condoms.
• There is increasing __similarities__ when moving down the classification table

  from kingdom to species.
• A cell was placed in a hypotonic solution for 15 minutes and then observed under the microscope. Apply the concept of osmosis to explain what happens to the cell after 15 minutes

  The water moves into the cell from lower solute concentration to a higher solute concentration by the process of osmosis making the cell turgid
• Genotype


  genetic identity of an organism
• Allele-


  variant form of a gene
• Dominant allele


  stronger allele which masks off the effect of recessive allele
• Recessive allele-


  weaker allele
• Describe how a test cross is carried out and state its purpose.

  It involves the breeding of an organism showing a dominant phenotype with a homozygous recessive organism  to determine whether the individual being tested is homozygous dominant (pure bred) or heterozygous
• Why is genetic variation important

  Genetic variation is important because a population has a better chance of surviving and flourishing than a population with limited/less genetic variation
• Different plants display different types of leaf arrangement such as spiral, whorl and alternate arrangements. Explain the importance of leaf arrangement to plants.


  To increase a plant’s ability to carry on photosynthesis  by positioning the leaves in such a way as to maximize the surface area available to capture sunlight  OR Leaf arrangements also directs water towards the root to be absorbed by the plant.
• State one function of a fibrous root.

   The roots of the plant spread out to absorb maximum surface water   They hold the plant firmly in the soil   It helps the plants to stand up firmly even when a strong wind blows
• State one environmental condition which is most suitable for seed germination.

  1. Water (or moisture)  OR 2. Oxygen/ air  OR 3. warmth (or suitable temperature
• What is the difference between hypogeal germination and epigeal germination?

  In epigeal germination, the sprouting seed leaves rise above ground level  while in hypogeal germination, seed leaves emerge from the seed and remain underground or at ground level
• State the role of stomata in relation to water movement in plants.

  Stomata in the plants regulate the amount of water by opening and closing their guard cells
• Explain how the closure of stomata would affect the rate of photosynthesis

  and plant growth.

  Slow down the rate of photosynthesis (1 mark) due to less carbon dioxide uptake/ less gas exchange.
• State one benefit of artifiial selection

  Produced plants that are resistance against weather and pests
• State one ecological importance of plants

  Produce oxygen through photosynthesis
• define cross-pollinatio


  The transfer of pollen grain from the male reproductive organ (an anther) of one plant to the female reproductive organ (a stigma) of another plant
• Self- pollination


  is the transfer of the pollen grains from the anther to the stigma of either the same flower or different flower on the same plant
• How insect pollinated flowers support pollination

  -Large, brightly colored petals

  • often sweetly scented