Some plants, such as roses, have thorns on their stems or branches. How do these act as an adaptation? A. To stop animals from eating the stems
B. To produce more oxygen from photosynthesis
C. To attract insects
D. To produce more food

Some plants, such as roses, have thorns on their stems or branches. These act as A. To stop animals from eating the stems.

A. To stop animals from eating the stems

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.