Key Stage 3 National Strategy Science pulmonary vein aorta digestive system heart pulmonary artery lungs liver kidneys rest of body upper limbs and head The mammalian circulatory system Slide 3.12

Key Stage 3 National Strategy Science red blood cell white blood cell red blood cell platelet red blood cell white blood cell plasma red blood cell white blood cell platelet Blood cells Slide 3.14

Key Stage 3 National Strategy Science Slide 4.21 upper epidermis mesophyll lower epidermis wax cuticle palisade mesophyll wax cuticle chloroplast spongy mesophyll air space stoma guard cell Diagram of cross-section of a leaf

Key Stage 3 National Strategy Science nuclear membrane Parent cell with 4 chromosomes. Chromosomes replicate forming pairs of chromatids. Pairs of chromosomes arrange themselves in the centre of the cell. The chromosomes separate and move to opposite ends of the cell. The first cell division occurs. The chromosomes now separate from each other and move to opposite ends of the cells. The second cell division occurs. Sex cell division Slide 4.29

Key Stage 3 National Strategy Science Determining sex in humans Male parent provides sperm with either an X or Y chromosome. Female parent provides eggs with an X chromosome. The possible combinations in the offspring are: Male parent Female parent X X X Y X X X X X X Y Y Slide 4.31