definitions - set 6

Question 1

phagocytes

Answer 1

white blood cells that surround, engulf and digest pathogens

Question 2

phenotype

Answer 2

the physical or other features of an organism due to both its genotype and its environment (e.g. tall plant or green seed)

Question 3

phloem tubes

Answer 3

long tubes made up of living cells with perforated end walls, which transport sucrose and other substances in plants

Question 4

photosynthesis

Answer 4

the process by which plants manufacture carbohydrates from raw materials using energy from light

Question 5

phototropism

Answer 5

a response in which a plant grows towards or away from the direction which light is coming

Question 6

placenta

Answer 6

in mammals, an organ made up of tissues of both the mother and embryo, through which the mother’s and embryo’s bodies exchange nutrients and waste materials

Question 7

plaque

Answer 7

a sticky film, containing bacteria, that builds up on teeth

Question 8

plasma

Answer 8

the liquid part of blood, in which the cells float

Question 9

plasmolysed

Answer 9

the condition of a plant cell that has lost so much water that its cytoplasm shrinks and pulls the cell membrane away from the cell wall

Question 10

platelets

Answer 10

tiny fragments of cells found in blood, which help with clotting

Question 11

plumule

Answer 11

the young shoot in an embryo plant

Question 12

pollen grains

Answer 12

tough, resistant structures containing the male gametes of a flower

Question 13

pollination

Answer 13

the transfer of pollen from the male part of the flower (anther of stamen) to the female part of the plant (stigma)

Question 14

polysaccharide

Answer 14

a carbohydrate whose molecules are made of hundreds of sugar units linked in long chains - for example, starch, glycogen and cellulose

Question 15

population

Answer 15

a group of organisms of one species, living in the same area at the same time

Question 16

predator

Answer 16

an animal that kills and eats other animals

Question 17

primary consumers

Answer 17

herbivores

Question 18

process of adaptations

Answer 18

the process resulting from natural selection, by which populations become more suited to their environment over many generations

Question 19

producer

Answer 19

an organism that makes its own organic nutrients, usually energy from sunlight, through photosynthesis

Question 20

product

Answer 20

the substance formed in an enzyme-controlled reaction

Question 21

progesterone

Answer 21

the pregnancy hormone; a hormone secreted by the ovaries and placenta which maintains the lining of the uterus

Question 22

prostate gland

Answer 22

a gland close to a male’s bladder, that secretes fluid in which sperm can swim

Question 23

protease

Answer 23

an enzyme that catalyses the breakdown of proteins

Question 24

puberty

Answer 24

the stage of development during which sexual maturity is reached

Question 25

pulmonary

Answer 25

relating to the lungs

Question 26

pure-breeding

Answer 26

homozygous

Question 27

pyramid of biomass

Answer 27

a sideways-on graph, in which the size of the boxes represents the dry mass of organisms in each trophic level of a food chain

Question 28

pyramid of numbers

Answer 28

a sideways-on graph, in which the size of the boxes represents the number of organisms in each trophic level of a food chain

Question 29

radicle

Answer 29

the young root in an embryo plant

Question 30

receptor

Answer 30

a cell that is able to detect changes in the environment; often part of a sense organ

Question 31

recessive

Answer 31

an allele that is only expressed when there is no dominant allele of the gene present (e.g. t or g)

Question 32

reducing sugar

Answer 32

a sugar that turns Benedict's solution brick red when heated

Question 33

reflex action

Answer 33

a fast, automatic response to a stimulus

Question 34

reflex arc

Answer 34

the arrangement of neurons along which an impulse passes during a reflex action

Question 35

renal

Answer 35

relating to the kidneys

Question 36

respiration

Answer 36

the chemical reaction in cells that break down nutrient molecules and release energy for metabolism

Question 37

retina

Answer 37

the part of the eye that contain receptor cells

Question 38

ribosome

Answer 38

tiny organelles where protein synthesis takes place

Question 39

rod cell

Answer 39

a light-sensitive cell in the retina, that responds to dim light

Question 40

root cap

Answer 40

a tough, protective covering over the tip of a root

Question 41

rough endoplasmic reticulum

Answer 41

a network of membranes inside a cell, on which ribosomes are present

Question 42

secondary consumers

Answer 42

carnivores that eat herbivores

Question 43

seed

Answer 43

an ovule after fertilisation; it contains an embryo plant

Question 44

selection pressure

Answer 44

an environmental factor that causes organisms with certain characteristics to have a better chance of survival than others

Question 45

self-pollination

Answer 45

the transfer of pollen form the anther to the stigma on the same plan (but not necessarily the same flower)

Question 46

semen

Answer 46

a mixture of sperm and fluids from the prostate gland a seminal vesicles

Question 47

seminal vesicles

Answer 47

glands that secrete fluid in which sperm can swim

Question 48

sense organs

Answer 48

groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals

Question 49

sensitivity

Answer 49

the ability to detect or sense changes in the environment (stimuli) and to make appropriate response

Question 50

characteristic (sex-linked)

Answer 50

characteristic in which the gene responsible is located on a sex chromosome, which makes it more common in one sex than in the other