PROCESSE S PHOTOSYNTHESIS CELLULAR RESPIRATION Plants absorb light

PROCESSE S

PHOTOSYNTHESIS & CELLULAR RESPIRATION

Plants absorb light energy from the Sun and convert it into chemical energy through photosynthesis. Photosynthesis produces sugar that the plant uses for food. Organisms need energy, which comes from cellular respiration—process of releasing energy by breaking down food

MAKING SUGARS BY USING LIGHT ENERGY Photosynthesis occurs in the leaves, which contain chloroplasts. Chloroplasts contain chlorophyll—a green pigment that absorbs light energy. That energy splits water molecules into hydrogen atoms and oxygen atoms. Some of the oxygen leaves through the stomata.

BREAKING DOWN SUGARS Cellular respiration breaks down the glucose during photosynthesis and releases the sugar’s energy. This occurs in the cytoplasm and mitochondria. Oxygen is also used during cellular respiration.

IMPORTANCE OF PHOTOSYNTHESIS & CELLULAR RESPIRATION The human body uses oxygen for cellular respiration. Cellular respiration breaks down food and stores the energy from food in ATP, which is used for cellular processes like: cellular growth, repair, and reproduction. During cellular respiration, carbon dioxide and water are given off as waste, but are used for photosynthesis in plants.

IMPORTANCE OF PHOTOSYNTHESIS & CELLULAR RESPIRATION Humans use the products of photosynthesis (oxygen and sugar) during cellular respiration. Plants benefit from the waste from cellular respiration (carbon dioxide and water) during photosynthesis. Plants also use some oxygen during their cellular respiration.

MOVEMENT OF NUTRIENTS & WATER

• Water and nutrients must move inside plants in order for them to carry on processes like photosynthesis and cellular respiration. • Nonvascular plants use osmosis and diffusion to move or transport materials. • Vascular plants use their specialized vascular tissues to move materials. (Osmosis and diffusion also play a role once the materials are outside of the vascular tissues)

ABSORPTION Roots and rhizoids of plants absorb water and nutrients from the soil. The water and nutrients move to cells, where they are used in cellular processes. Water is used for photosynthesis and the minerals are used for the compounds needed for cell growth and maintenance.

TRANSPIRATION Transpiration is the release of water vapor from stomata in leaves. This helps move water from the roots, up through the vascular tissue, and to the leaves. This helps provide water for photosynthesis and cool the plant on hot days.

PLANT RESPONSES

• Stimuli (stimulus)—are any changes in an organism’s environment that cause a response. • An example of a plant responding to stimuli would be the mimosa plant collapsing its leaves after being touched.

TYPES OF STIMULI Plants respond to internal and external stimuli. External Internal Plants includes: light, touch, and gravity. includes: chemicals, or hormones. produce different hormones that affect growth, seed germination, or fruit ripening.

TROPISM Definition: Plant growth toward or away from an external stimulus.

PHOTOTROPISMS When a plant grows toward a light source, it is called positive phototropism. Growing toward a light source enables leaves to receive the maximum amount of light. Roots exhibit negative phototropism by growing into the soil away from the light. This anchors the plant.

GRAVITROPISM This is a plant’s response to gravity. The first root produced by a germinating seed grows downward, which would be positive gravitropism. A plant’s stem grows upward and away from gravity, which would be negative gravitropism.

THIGMOTROPISM This is a plant’s response to touch. The coiling of a vine’s tendrils around another plant or object is an example of positive thigmotropism. A plant’s roots exhibits negative thigmotropism when they grow around a rock in the soil.